HARVARD UNIVERSITY

LIBRARY

OF THE

Museum of Comparative Zoology

S -- N A-^ti

University of Kansas Publications
Museum of Natural History

Volume 4, pp. 1-466, plates 1-41, 31 figures in text
December 27, 1951 ^ ' > ' '

AMERICAN WEASELS

BY
E. RAYMOND HALL

University of Kansas

Lawrence

1951

\

UNIVERSITY OF KANSAS PUBLICAUONS

The University of Kansas Publications, Museum of Natural His-
tory, are offered in exchange for the publications of learned societies
and institutions, universities and libraries. For exchanges and in-
formation, address the Exchange Desk, University of Kansas Li-
brary, Lawrence, Kansas, U. S. A.

Museum of Natural History. — E. Raymond Hall, Chairman, Editorial Com-
mittee.

This series contains contributions from the Museum of Natural History.

Cited as Univ. Kans. Publ., Mus. Nat. Hist.
Vol. 1. 1. The pocket gophers (genus Thoniomys) of Utah. By Stephen D.
Durrant. Pp. 1-82, 1 figure in text. August 15, 1946.

2. The systematic status of Eumeces pluvialis Cope, and noteworthy
records of other amphibians and reptiles from Kansas and Okla-
homa. By Hobart M. Smith. Pp. 85-89. August 15, 1946.

3. The tadpoles of Bufo cognatus Say. By Hobart M. Smith. Pp.
93-96, 1 figure in text. August 15, 1946.

4. Hybridization between two species of garter snakes. By Hobart
M. Smith. Pp. 97-100. August 15, 1946.

5. Selected records of reptiles and amphibians from Kansas. By John
Breukelman and Hobart M. Smith. Pp. 101-112. August 15, 1946.

6. Kyphosis and other variations in soft-shelled turtles. By Hobart
M. Smith. Pp. 117-124, 3 figures in text. July 7, 1947.

7. Natural history of the prairie vole (Mammalian genus Microtus).
By E. W. Jameson, Jr. Pp. 125-151, 4 figures in text. October 6,
1947.

8. The postnatal development of two broods of great homed owls
(Bubo virginianus ) . By Donald F. Hoffmeister and Henry W.
Setzer. Pp. 157-173, 5 figures in text. October 6, 1947.

9. Additions to the list of the birds of Louisiana. By George H.
Lowery, Jr. Pp. 177-192. November 7, 1947.

10. A check-list of the birds of Idaho. By M. Dale Ar\ey. Pp. 193-
216. November 29, 1947.

11. Subspeciation in pocket gophers of Kansas. By Bernardo Villa-R.
and E. Raymond Hall. Pp. 217-236, 2 figures in text. November
29, 1947.

12. A new bat (genus Myotis) from Mexico. By Walter W. Dalquest
and E. Raymond Hall. Pp. 237-244, 6 figures in text. December
10, 1947.

13. Tadarida femorosacca (Merriam) in Tamaulipas, Mexico. By
Walter W. Dalquest and E. Raymond Hall. Pp. 245-248, 1 figure
in text. December 10, 1947.

14. A new pocket gopher (Thomomys) and a new spiny pocket mouse
(Liomys) from Michoacdn, Mexico. By E. Raymond Hall and
Bernardo Villa-R. Pp. 249-256, 6 figures in text. July 26, 1948.

15. A new hylid frog from eastern Mexico. By Edward H. Taylor.
Pp. 257-264, 1 figure in text. August 16, 1948.

(Continued on inside of back cover.)

i

University of Kansas Publications
Museum of Natural History

Vol. 4, pp. 1-466, plates 1-41, 31 figures in text
December 27, 1951

AMERICAN WEASELS

BY

E. RAYMOND HALL

. cm. Z88L

MAR 1 7 1952

iMAR 1

University of Kansas

Law^rence

1951

University of Kansas Publications, Museum of Natural History

Editors: E. Raymond Hall, Chairman, A. Byron Leonard,
Edward H. Taylor, Robert W. Wilson

Vol. 4, pp. 1-466, plates 1-41, 31 figures in text
December 27, 1951

University of Kansas
Lawrence, Kansas

PRINTED BY

FERD VOILAND. JR.. STATE PRINTER

TOPEKA. KANSAS

1951

23-3758

AMERICAN WEASELS
(3)

Plate 1.

Ha*n&r**^

30

20

10, _ '

120

T

100

(1 / ■ I — ^. - •

.•'OREGON. Tillamook. M.f.altifrontalis. 38AW, Coll. of S. J. Jewett.

• CALIFORNIA, Point Arena. M.f.munda, 19722, M V.

^-

\ A —

8 ■<
(CALIFORNIA, West Riversi(

1. < 7 ' '

' ■ •ARIZONA Sofford. M.f.neomexicana, 204365, U.S. N^M.

;ide. M. f. la h rostra, 7143", M. V. Z.-^'T— „.

r "v

>^,

.-30

r C \ ^!"«iTAMAULIPAS, Motomoros. M. f. frenata, 1 16552 , U. S. N.M

V^; y-- > / r

-A^ • MICHOACAN Los Reyes. M.f. leucopana, 125972, U.S.N.M.

GUATEMALA, G Sto. Elena. M. f. goldmani, 15953, FM

NICARAGUA, fi/latogaipa. M.f.nicaraguae. 28322, A.mTnh'«

PANAMA, Mt. Pirre. M.fpanamensis,\7Q970,\J.S.H.f<Ji^ —

100 100 300
I n i I I -t—

600 MILES

PERU, Loke Junin. M.f.macroura, ttie type. •
1 1 , \

no

90

Fig. 1. Map showing localities of capture of specimens depicted in plate 1.

Plate 1. Coloration of head and foreparts in ten subspecies of long-tailed
weasel, Mustela frenata. All figures are of males, approximately X Js.

In regions of heavy rainfall ( see figs. 2 and 3 ) there is an increase in
pigmentation and extent of blackish color backward over the neck and a
decrease in extent of the white facial markings. In regions progressively more
arid ( see figs. 3 to 7 ) there is a decrease in pigmentation and extent of blackish
color and an increase in extent of the white facial markings.

As shown by rearing mammals from humid regions in arid regions, and
vice versa, the color is not visibly altered in one or a few generations; the
color is an hereditary character. Beginning with the southernmost subspecies
( fig. 1 ) and continuing northward to the northern subspecies ( fig. 10 ) there
is a darkening, next a hghtening, and finally a darkening closely conforming
to amounts of precipitation in the geographic regions concerned. A fuller dis-
cussion of this correlation is given on page 51.

(5)

American Weasels

BY

E. RAYMOND HALL

CONTENTS

PAGE

iNTRODUCnON 7

Paleontological History 10

Skeleton and Dentition 12

Disparity in Number of Males and Females 19

Materials, Acknowledgments and Methods 21

Variation 24

Variation with Age 24

Secondary Sexual Variation 26

Individual Variation 28

Seasonal Variation 30

Variation in Coloration and Molt 30

Variation of Taxonomic Worth 44

Distribution and Speciation 54

History of Classification 69

Chronological List (annotated) of Specific and Sub-
specific Names 71

Check List of American Species and Subspecies of the Genus
Mustela 81

Artificial Key to American Species of the Genus Mustela, 83

Diagnosis of the Genus 83

Explanation of Systematic Treatment 84

Systematic Accounts of Species and Subspecies 87

Mustela erminea 87

Mustela rixosa 1 68

Mustela frenata 193

Mustela africana 406

Explanation of Cranial Measurements 417

Table of Cranial Measurements 418

Literature Cited 442

Index 461

(6)

American Weasels

By E. Raymond Hall

INTRODUCTION

THE weasel's agility and speed take it in and out of retreats, over
obstacles and across open places in amazingly rapid fashion
and are responsible for the animal's actions being described as
"quick as a flash," The common long-tailed weasel of the United
States measures approximately a foot and a half in length, of which
the tail comprises a third; but the round, slender body is scarcely
more tlian an inch and a half in diameter. Brown above and whitish
below in summer dress, the animal is sleek as well as lithe and grace-
ful. It is easy to understand, therefore, why the Bavarian name
Schonthierlein (pretty little creature) and the Italian name donnola
(little lady) were bestowed upon it. The Spanish name is coma-
dreja (godmother).

In the winter, in temperate and northern regions, the coat be-
comes pure white except for the black tail-tip. In this dress the
correct name for the animal is ermine, a mammal whose fur is
known to all and justly esteemed, especially for its luster in arti-
ficial light, where it is scarcely excelled in enhancing the beauty
of gems and their feminine wearers.

In relation to its weight, the weasel is thought to be unsurpassed,
and perhaps it is unequalled among mammals, in the effectiveness
with which it exercises its carnivorous heritage; it kills with speed
and strength a wide variety of animals including many much larger
than itself; and it has been known to attack even man himself when
he stood between the weasel and its intended prey. In structure
and temperament it is so highly specialized for offense that, when
opportunity affords, it sometimes kills, for storage in its larder, far
more than enough to meet its immediate needs. After speaking
of this tendency, Elliott Coues (1877:129) has said:

"A glance at the physiognomy of the weasels would suffice to
betray their character. The teeth are almost of the highest known
raptorial character; the jaws are worked by enormous masses of
muscles covering all the side of the skull. The forehead is low and
the nose is sharp; the eyes are small, penetrating, cunning, and

(7)

8 University of Kansas Publs., Mus. Nat. Hist,

glitter with an angry green light. There is something peculiar,
moreover, in the way that this fierce face surmounts a body extra-
ordinarily wiry, lithe, and muscular. It ends in a remarkable long
and slender neck in such a way that it may be held at right angle
with the axis of the latter. When the creature is glancing around,
with the neck stretched up, and flat triangular head bent forward,
swaying from one side to the other, we catch the likeness in a mo-
ment — it is the image of a serpent." Although Coues' colorful de-
scription more closely links the weasel with the symbol of evil than
pleases me, his description does emphasize the raptorial character
of the weasel.

Even though most weasels are intractable as pets, they have a
value to man, as, for instance, when he is plagued by mice. In a
field where mice and other small rodents are so abundant as to
damage cultivated crops, the weasel is the farmer's best friend. A
weasel may inhabit one den until the rodents thereabouts are al-
most exterminated in an area two or three hundred yards across;
in this way the weasel acts as a control, locally, as well as a check
more widely, on the increase in size of populations of kinds of
rodents upon which it preys. The smaller species are mousers of
remarkable eflBciency and can, if necessary, follow a mouse to the
end of the mouse's burrow. The slender body allows the weasel
to pass through any burrow or hole into which it can thrust its
head. This ability in an organism as highly specialized for killing
other animals as is the weasel, has earned for it a bad name in con-
nection with poultry yards. Authentic instances are recorded in
which a weasel, gaining entrance through a knot-hole to a coop of
young chickens, killed several dozen of the fowls. In other in-
stances, however, weasels have lived under buildings close by a
poultry yard without even molesting the birds in the slightest; in the
latter instances the weasels probably were present because there
was an abundant supply of rats and mice. At least three poultry
raisers ( see page 214 ) have encouraged weasels to live in their poul-
try yards feeling that the good they do by destroying rats outweighs
the damage caused by the occasional weasel which turns to the
fowls; the idea is that the individual weasel can be eliminated if he
becomes destructive.

Although tending to be nocturnal, weasels are almost as active
by day as by night. Their young, numbering 4 to 9, are bom in a
nest in a burrow and as with other members of the Order Carnivora,
are bhnd and incapable of looking after themselves at the time of
birth. In Mustela frenata of Montana, breeding occurs in July and

Introduction 9

August, and the young are born in the following April and May.
Wright (1948A:342) showed that the gestation period could not
have been less than 337 days in one individual and that it averaged
279 (205-337) days in 18 instances. Findings of the same author
(1942B:109) showed that the embryos are implanted only 21 to
28 days before the young are bom. In the preceding part of the
"long gestation period, the embryos lie dormant in the uterus as
unimplanted blastocysts. The young female weasel [of M. frenata]
mates when 3 or 4 months old." Consequently, in the spring, all
females of this species may produce young (Wright, 1942A:348).
The circumboreal species Mustela erminea likewise has been shown
to have a delayed implantation of the ova. Each of these two spe-
cies, M. frenata and M. erminea, has only one litter per year; but
the weasel, Mustela nivalis, of the Old World seems to lack the de-
layed implantation, in this respect resembling the ferret (subgenus
Putorius) as it does also in its ability to have more than one litter
per year ( see Deanesly, 1944 ) . The manner of reproduction in the
South American species M. africana and the circumboreal species
M. rixosa at this writing is unknown.

The genus Mustela includes the true weasels, the ferrets and
minks. The ferrets commonly are treated as a subgenus, Putorius,
along with the Old World polecat. The minks usually are accorded
subgeneric distinction under the name Lutreola, and the true
weasels comprise the subgenus Mustela, the three subgenera to-
gether, along with some other subgenera which are mostly mono-
typic, comprising the genus Mustela. Considered in this way, the
group of true weasels, subgenus Mustela, has a geographic range
roughly coextensive with that of the genus Mustela. This range in-
cludes Asia and Europe, Northern Africa, North America and north-
em South America. Java has its weasel. Australia and nearly all
the oceanic islands lack weasels, and the animals are absent from
roughly the southern half of Africa and the southern half of South
America. Other small mustelids, weasellike in shape and with
corresponding habits and dentition, take the place of true Mustela
in the southern half of Africa and in the corresponding part of South
America.

In America the subgenus Mustela occurs from the northernmost
land in Arctic America southward to Lake Titicaca in the Andes
of South America, a distance of approximately 6900 miles. Felis,
I think, is the only other genus of land mammals in the western
hemisphere that has a geographic range as extensive from north to
south. Felis does not range so far north but does range farther

10 University of Kansas Publs., Mus. Nat. Hist.

south. The one species, Mtistela frenata, ranges from Lake Titicaca
northward to about 57° N in British Cokimbia or for approximately
5000 miles in a north to south direction and from within the Alpine
Arctic Life-zone through the Tropical Life-zone. In North Amer-
ica, weasels occur in almost every type of habitat, being absent only
in the extremely desert terrain of western Arizona and western
Sonora and in adjoining parts of California and Baja California.
Even this area, along the Colorado River, may support some weasels;
evidence suggesting that it does so is given in the account of
Mustela frenata neomexicana.

PALEONTOLOGICAL HISTORY

The paleontological record fails to show the precise ancestry of
Mustela. The genus has been found in deposits of Pleistocene age,
but, so far as I can ascertain, not in deposits of earlier times. The
Pleistocene remains are not specifically distinct from Recent (living)
species, and in only a few instances (see M. /. latirostra and M. e.
angustidens) are they even subspecifically distinct from the Recent
weasel living in the same area today. It is true that fossil remains
from deposits of several stages of the Tertiary beds have in the
past been identified in the literature as Mustela, but most of these
identifications were made many years ago when the generic name
Mustela was used in a far broader and more inclusive sense than it
is today and much of the fossil material was so fragmentary that
the generic identity could not be ascertained, at least at that time.
Because the generic identity could not be ascertained, the fossil ma-
terial was tentatively assigned to the genus Mustela, the "typical"
genus of the family Mustelidae instead of to some other more spe-
cialized or less well-known genus of the family. To satisfy my
curiosity about these species of "Mustela" of a geological age earlier
than the Pleistocene I have personally studied nearly all of the orig-
inal specimens from North America and have found each to be of
some genus other than Mustela. Also, such study as I have been
able to make of the Old World fossils themselves that have been
referred to the genus Mustela up to 1938, and my study of the illus-
trations and descriptions of the others from there lead to the same
conclusion; that is to say, none that is true Mustela is known up to
now from deposits older than the Pleistocene.

When, in 1930 (pp. 146-147), I wrote about the taxonomic po-
sition of three American genera of fossils (known only from lower
jaws), each of which had been previously referred to the genus
Mustela^ I said that they pertained "to that section of the weasel

Paleontological History 11

family (Mustelidae) which comprises the polecats, true weasels,
ferrets, minks and martens. The fossil specimens . . . are
smaller than any other later Tertiary members of the group yet
described, and are more primitive than any of the above mentioned
Recent relatives. Of the three extinct genera . . . Miomustela
[Lower Pliocene or Upper Miocene of the Lower Madison Valley,
Montana] is the most primitive and Martinog,ale [Pliocene, 18 mi.
SE Goodland, Sherman County, Kansas] is the most advanced.
This view rests largely on the character of My which in Miomustela
has a deeply basined, short, narrow talonid with a thick, high
metaconid situated partly posterior to the protoconid. In Martino-
gale the talonid is incipiently trenchant, long, broad, and it has
a lesser developed metaconid which is situated more anterior [ly].
Pliogale [Lower Pliocene, Humboldt County, Nevada] is inter-
mediate in this respect.

"These three forms are of special interest as possible ancestors
of the subgenus Mustela, true weasels. No members of this sub-
genus, nor related forms which can with any degree of certainty
be regarded as directly ancestral to them, have yet been described
from Miocene or Pliocene deposits. Palaeogale of the Old World
and Bimaelurus of North America, each of Oligocene age, have
been placed by Schlosser (1888, p. 116) and Matthew (1902, p. 137)
as members of the primitive group of mustelids ancestral to Mustela.
This course seems logical; and with no truly intermediate links
between these forms of the Oligocene on the one hand, and Mustela
which first appears in the Pleistocene, on the other, more definite
statements about ancestral positions of the small Oligocene forms
can hardly be made. The deciding considerations for authors who
placed Palaeogale and Bunaelunis as ancestral to Mustela were the
absence of a metaconid on Mj and the trenchant talonid of that
tooth. These characters are found also in Mustela. On the other
hand certain structures in the basicranial region of Palaeogale and
more especially of Bunaelunis indicate that these genera possibly
are not close to the ancestral form of Mustela .... Martinogale
may stand near the ancestral form of Mustela and . . . Pliogale
may be ancestral to Martinogale. Pliogale, in turn, may have
had an ancestor similar to Miomustela. If this should prove to
be the case, Palaeogale and Bunaelurus might be regarded as an
independent branch which displays merely a parallelism to Mustela
in the loss of the metaconid on M , and the development of a trench-
ant talonid on that tooth. The writer would make it clear that

12 University of Kansas Publs., Mus. Nat. Hist.

he does not hold such to be the case. The ancestral relation
of Martinogale to Mustela is presented merely to show the pos-
sibility, and not the special probability, of such an origin for
Mustela. Knowledge of the tympanic bullae and other structures
of the basicranial region would go far toward answering the ques-
tion and until these structures are known [in mustelids of the
Later Tertiary,] some uncertainty will remain."

At the present writing I can add to the above statement only
a few facts. The discovery of better material of Bunaelurus than
was available to previous workers led Simpson ( 1946 ) , correctly
I think, to synonymize Bunaelurus with Palaeogale. Simpson fig-
ures the cranial foramina in Palaeogale. The differences, between
Palaeogale and Mustela, in cranial foramina, possibly are only the
result of the elongation of the tympanic bullae. The bullae of
the subgenus Mustela are seen to be much elongated posteriorly
if comparison is made with the bullae of earlier mustelids. Con-
sequently, it might be concluded that there is nothing in the
arrangement of the cranial foramina which would preclude the
derivation of Mustela from Palaeogale. However, the anterior
situation of the carotid foramen — well forward along the medial
margin of the tympanic bulla — is a character typical of other muste-
lids and the posterior location of this foramen in Palaeogale might
indicate that it was not ancestral to Mustela.

SKELETON AND DENTITION

The outstanding features of a weasel's skeleton are its length
and slenderness. Whereas the length of the vertebral column
measured from the atlas (the first cervical vertebra) to the last
sacral vertebra is 175 per cent of the length of the hind leg (as
measured from the head of the femur to the tip of the longest
claw), the corresponding percentage is only 116 in the raccoon.
Stated in another way, the vertebral column and the hind leg are
of approximately equal length in a raccoon, but in a weasel the
vertebral column is one and three-fourths times as long as the
hind leg.

VERTEBRAE

The vertebral column consists of 7 cervicals, and ordinarily 14
thoracics, 6 lumbars, 3 sacrals and, depending on the species, 11 to
23 caudals. For the three species of which skeletons were exam-
ined, variations from the normal number of vertebrae are noted in
the following table:

Skeleton and Dentition

13

Table 1
Data on vertebrae in three species of the subgenus Mustela

(Numerals in parentheses indicate number of specimens)

Mustela erminea

Mustela rixosa

Mustela frenata

Number of cervical
vertebrae

(75)
7

(12)
7

(65)

7

Number of thoracic
vertebrae

(71)
14

(12)
14

(54)
14

(4)
15

(13)
15

The dorsal vertebra
constituting the
anticlinal ...

(18)
11th

(12)

nth

(40)

nth

(7)
12th

(27)
12th

Number of lumbar

(2)
5

(11)
5

vertebrae

(73)
6

(12)
6

(54)
6

(9)
2

(3)
2

Number of sacral
vertebrae

(65)
3

(10)
3

(67)
3

(1)
4

(2)
4

Number of pseudosa-
cral vertebrae

(73)

(12)

(57)

(2)

1

(6)
1

(1)
11

(3)
14

(2)
15

(7)
15

(3)
16

(1)
16

(9)
17

Number of caudal
vertebrae

(28)
18

(11)
19

(6)
19

(14)
20

(14)
21

(7)
22

(1)
23

14 University of Kansas Publs., Mus. Nat. Hist.

Variation according to the species is evident in the number of
caudal vertebrae, but in the other categories of vertebrae no con-
sistent difference in number according to species was found in the
material examined. Apparently there is also some geographic varia-
tion in the number of caudal vertebrae within a species. For exam-
ple, the one skeleton seen of Mustela rixosa eskimo (no. 219036,
U. S. Nat. Mus., from St. Michaels, Alaska) has only 11 caudal
vertebrae, whereas in the 11 Mustela rixosa rixosa from Roseau
County, Minnesota, the usual number is 15 with extremes of 14
and 16. Similarly specimens of Mustela frenata from Idaho and
California almost always have 1 or 2 more caudal vertebrae than
do individuals of the shorter-tailed subspecies of the same species
from eastern Kansas.

Of the vertebrae, only the cervicals, of which there are 7, were
found to be constant in number. In M. erminea, two of the seven
individuals in which the anticlinal vertebra was the 12th (instead
of the 11th) had 15 instead of the customary 14 thoracic vertebrae.
In M. frenata, seven of the twenty-seven individuals in which the
anticlinal vertebra was the 12th (instead of the 11th) had 15 instead
of 14 thoracic vertebrae. The one M. erminea with a pseudosacral
vertebra had only two instead of the customary 3 sacral vertebrae
but the same individual had 15 thoracic vertebrae. Of the six M.
frenata with a pseudosacral vertebra, two animals had only two
instead of three sacral vertebrae. Conceivably, therefore, the pseudo-
sacral vertebra in each of the three instances mentioned may rep-
resent merely an unfused sacral vertebra, instead of a true pseudo-
sacral as occurs in four individuals of M. frenata.

TEETH
In American weasels, for example in Mustela frenata, the per-
manent dentition normally is — , — ; — , — ; — , — ; — , _ , or 34 teeth in

i 3 c 1 p 3 m 2

all. In most respects the dentition is typical for post-Tertiary
mustelids but in several parts is highly specialized for a diet of
flesh, the degree of this specialization being second only to that of
the cats, family Felidae. The outstanding specialization is in the
first lower molar, in which, as in the cats, the internal cusp (meta-
conid) is completely suppressed and the heel (talonid) forms an
elevated blade for cutting food rather than a basin for crushing it.
In one sense the tooth is simplified since it owes its distinctive form
to a reduction in number of parts; nevertheless, the distinctive form
of the lower molar clearly is correlated with a diet of flesh, and the

Skeleton and Dentition 15

tooth is correctly to be thought of as the lower blade of a pair of
shears; the upper blade is the fourth upper premolar. The re-
duction in size of the second (last) lower molar and small size of the
inner lobe of the one remaining upper molar probably are addi-
tional modifications for a diet of flesh.

Tlie absence of the last two upper molars and last molar in the
lower jaw would be expected in any mammal as highly specialized
for a diet of flesh as is the weasel, but these teeth are absent also
in otlier Quaternary members of the family Mustelidae, many of
which are substantially less specialized for a diet of flesh than is the
weasel. Therefore, in the weasel, it is reasonable to regard the
absence of these teeth more as a heritage than as an indication of a
special adaptation. The absence of a first premolar above and
below, as in the weasel, is to be expected in any carnivore that has
the first lower molar and fourtli upper premolar highly specialized
for shearing, but the loss of these premolars and the small size of
the second premolars may be as much the result of a slight shorten-
ing of the face as it is a result of a lengthening of the third and
especially the fourth premolars. The lengthening of these more
posteriorly-situated teeth would appear to be an adaptation to a
diet of flesh. The cause of the lengthening of the mentioned teeth
and the reason for the absence of the first premolars probably will
be unknown until the fossil record is more complete.

The teeth of American species vary little except in size. The
absence of P2 in Mustela africana is the only difference of a qualita-
tive (presence or absence) nature that was detected. Also, tlie
Central American subspecies of Mustela frenata exhibit a tendency
to early loss of P2 and thus foreshadow the condition typical of
M. africana.

As a whole the dentition of the weasel exhibits a high degree of
specialization for a diet of flesh and this specialization is fully as
evident in the deciduous dentition as in the pennanent dentition.

The deciduous, or milk, dentition, of Mustela frenata, as known
from immature specimens of Mustela frenata noveboracensis and
Mustela frenata frenata available for this study, is comprised of
canines, one on each side above and below, and 3 cheek teeth on
each side above and below. See figures 2-9. The upper cheek
teeth from anterior to posterior are: a minute peglike tooth in gen-
eral similar to the first premolar of the permanent dentition; a shear-
ing tooth in general similar to P4 of the permanent dentition; and an
anteroposteriorly compressed tooth in general similar to Ml of the
permanent dentition. In the lower jaw, behind the canine, there is

16 University of Kansas Publs., Mus. Nat. Hist.

first a minute peglike tooth, second a two-rooted tooth similar in
general outline to a permanent third premolar, and finally a shear-
ing tooth corresponding in function to ml of the permanent denti-
tion.

No postnatal specimens which show deciduous incisors have
been examined.

Selected, outstanding differences between the permanent teetli
and the deciduous teeth are as follows: In the deciduous teeth the
canine above has on the posterior face a well-defined ridge extend-
ing from the tip to the cingulum. This ridge is absent or at most
faintly indicated in the permanent tooth. The lower deciduous
canine, in cross section is seen to have a marked indentation on the
anteromedial border in the region of the cingulum; this indenta-
tion is lacking in the permanent tooth. The anterior one of the
deciduous cheek teeth, both above and below, is single rooted and
its crown-surface is only about one-fifteenth as much as that of the
anterior premolar of the permanent dentition. The second decid-
uous cheek tooth below has two roots, usually fused, and diflFers
from p4 of the permanent dentition in having the tip of the prin-
cipal cusp more recurved, in having the anterior basal cusp better
developed and the posterior heel less well developed.

The second deciduous cheek tooth above corresponds in function
and general plan of construction to P4 of the permanent dentition
but difi^ers from that tooth in the more pronounced protostyle,
longer tritocone, more posteriorly located deuterocone and as noted
by Leche (1915:322) separation of the protocone and tritocone
by a notch. The third upper deciduous tooth has a single cusp in-
ternally and two cusps laterally. Thus it reverses the relation of
parts seen in Ml where the internal moiety is larger than the lateral
or buccal moiety. The third deciduous tooth below differs from
ml in very much shorter talonid and separation of the paraconid
from the protoconid by a deeper notch.

All the features in which the last two deciduous teeth, both above
and below, are described as differing from their functional counter-
parts in the permanent dentition, are features found in the per-
manent teeth of primitive fossil mustelids and certain fossil and
Recent viverrids. Even so, taking into account Leche's (1915)
work, which shows that the milk teeth of some carnivores have
structures lacking in the corresponding permanent teeth of the
same individual animal and also in the teeth of genera that seem
to be ancestral, a person suspects that some of the structural fea-

Skeleton and Dentition

17

Figs. 2-9. Views of permanent and deciduous teeth of Mustela frenata
nigriauris. Incisors not shown. In each instance teeth are of the left side.

Permanent dentition X 3. No. 32421, Mus. Vert. Zool., $ , adult; Berkeley,
Alameda County, California; obtained October 4, 1921, by D. D. McLean.

Deciduous dentition X 5. No. 132158, U. S. Nat. Mus., S , juvenile; Stan-
ford University, Santa Clara County, California; obtained May 7, 1898, by
W. K. Fisher.

Figs. 2-3. Lateral views of upper teeth, of adult and juvenile respectively.

Occlusolingual views of upper teeth of adult and juvenile respec-

Figs. 4-5.
tivcly.

Figs. 6-7.

Figs. 8-9.
tively.

Lateral views of lower teeth of adult and juvenile respectively.
Occlusolingual views of lower teeth of adult and juvenile respec-

tures mentioned above are not inheritances of ancestral conditions
but rather speciahzations of the milk dentition.

In other deciduous teeth there is clearer evidence of more spe-
cialization for a diet of flesh in the deciduous teeth than in the per-
manent teeth. For example, the upper carnassial of the milk den-

18 University of Kansas Publs., Mus. Nat. Hist.

tition is even more highly sectorial than is the permanent tooth and
strikingly like that of some of the cats. The lower tooth that is
effective in the shearing action bears no more trace of the metaconid
than does the permanent first lower molar. These features of the
deciduous dentition suggest that it is more specialized for a diet of
flesh than is the permanent dentition. If this be the fact, it may
seem especially remarkable because the commonly employed term
"milk teeth" suggests that the animal makes but little or no use of
these teeth in the short time that they are in place. Accordingly,
the student may credit the form of these teeth more to some indi-
rect effects of inheritance than to natural selection acting directly
upon the teeth. But, after all, natural selection probably is re-
sponsible for the form of these teeth as is indicated by the observa-
tions of Hamilton (1933:318-325). He found that these milk teeth
are used for eating solid food as soon as the principal shearing
teeth are in place. This is three weeks after birth and before all
of the deciduous teeth have broken through the gums. These
shearing teeth are used for almost two months before being re-
placed by the permanent teeth and it is, therefore, evident that
natural selection could operate to fully as great a degree in deter-
mining the form of the deciduous teeth as it may with the perma-
nent teeth.

Hamilton (1933:325-326) found that the permanent dentition was
complete at 75 days after birth in captive specimens of Mustela
frenata noveboracensis. In the same subspecies, he noted 28 days
after birth that the canines and carnassial teeth [second deciduous
cheek tooth above and third below] had erupted through the gums.
Animals 45 days old, Hamilton found, were losing the milk denti-
tion, and had the gums broken through by several of tlie perma-
nent cheek teeth.

Study of the cleaned skulls available of juveniles indicates that the
deciduous teeth which persist longest are, on each side of the mouth,
the second cheek tooth above and the third cheek tooth below. These
teeth persist until after the permanent P4 and ml have come into
use. These permanent teeth are situated immediately behind their
functional coimterparts of the milk dentition. P3 and p4 are the
teeth of the permanent dentition which ultimately push out the
last milk teeth to be lost. Accordingly, in the permanent dentition,
P4 and Ml appear before P3 does, and ml and m2 make their
appearance before p4.

Disparity in Number of Males and Females 19

DISPARITY IN NUMBERS OF MALES AND FEMALES
(IN ZOOLOGICAL COLLECTIONS)

The question has frequently been asked why twice as many male
as female weasels are captured. This is the proportion in research
collections, as may be seen from table no. 2, and I am convinced
that the specimens in these collections are saved in approximately
the same proportion as that in which they are caught. Although
it might be assumed, upon first consideration, that there are twice
as many males as females in nature, selective factors enter into the
catch. For example, because a male weasel is approximately twice
as heavy as a female, it may be necessary for him, in a given length
of time, to travel twice as far as the female to obtain the required
amount of food witli the result that a given number of traps or
snares will catch twice as many males as females. Indeed, Glover
(1943B:8) shows that, on the average, in Mustela frenata nove-
boracensis in Pennsylvania, the male actually does travel slightly
more than twice as far as the female (704 feet versus 346 feet).
From table no. 2, it may be seen that in most winter months the
ratio is 3 males to one female. This ratio is reasonable enough, in
view of what has been said, if it is considered also that the lighter
weight of the female permits her safely to step on the pans of traps
that would be sprung by heavier males.

If in the breeding season, which is April through August in
M . frenata, the female is passive and if the male is restlessly search-
ing for her, he may thus increase still more his chances of being
caught in traps set for weasels.

My own studies of live weasels in nature indicate that in the sea-
son when females are attending young which are half grown, or
larger, the adult male weasels live singly in dens of their own,
separate and apart from the females and their young (Hamilton,
1933:328, records adult males living with the female and her young,
but possibly this was when the young were less than half grown).
Perhaps these males at that time travel no farther than is necessary
to obtain food for themselves. Females, at this time, forage not
only to meet their own needs, but for food to supply their young as
well. At this time, in May and June, as may be seen from table
no. 2, almost as many adult females as adult males are caught. The
reason why only relatively more females than in other months, in-
stead of actually more females than males, are caught at this time
probably is that the adult males also are extraordinarily active at

20

University of Kansas Publs., Mus. Nat. Hist.

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Materials, Acknowledgments and Methods 21

this time because they are in breeding condition. Perhaps the ex-
planation in part is to be found in the lesser weight of the female
(approximately half of the male's weight) which, as indicated
above, permits her to step on the pan of a steel trap without spring-
ing it whereas the heavier male does spring the trap and as a con-
sequence is caught. Hamilton (1933:299-300), who mentions this
selective factor, found an equal number of males and females in
the three newly born litters that came under his observation.

I suppose that in nature there are approximately equal numbers
of male and female weasels and further suppose that the selective
factors which cause more males tlian females to be caught are the
greater distances traveled by the males and their greater weight.

MATERIALS, ACKNOWLEDGMENTS AND METHODS

At a late stage in the preparation of this manuscript a total of
5,457 specimens had been examined. For the most part these were
conventional study-specimens; that is to say, they were stuflFed skins
with the skulls separate and each was accompanied by the cus-
tomary data as to locality of capture, date of capture, name of col-
lector, external measurements and sex recorded on the labels by
the collectors. Skulls unaccompanied by skins, nevertheless, com-
prised a large share of the total and a small proportion was made
up of skins unaccompanied by skulls, mounted specimens, skeletons,
and entire animals presei"ved in liquid.

It was the recognition of this need for specimens from extensive areas from
which no specimens previously had been collected that influenced me, appro.xi-
mately a year after the study was begun, to allot for it a long span of time.
The procedure adopted, in general, was to study the weasels of one species
from a given geographic area in so far as the material warranted, then lay
this aside until additional critical material could be obtained, and finally, some
months or a year later, complete the account. In this fashion the manuscript
of the American weasels received my attention in each of the past twenty-five
years (September, 1926 to date of pubhcation). This is a confession of fact
rather than a recommendation of procedure. This type of procedure unduly
delays the diffusion of knowledge and for a variety of reasons justifiably annoys
other students of the subject. Nevertheless, many gaps have been filled that
otherwise would have remained open. Although specimens to solve several
problems still remain to be collected and studied, it seems that a point of
diminishing returns has now been reached, which, in fairness to all concerned,
calls for pubhcation of the results so far obtained.

For assistance in the entire undertaking, I am more indebted to Miss Annie
M. Alexander than to any other one person; she provided the means by which
specimens from critical areas were obtained, made it possible to examine the
European collections, and assisted in other ways. The late Professor Joseph

22

University of Kansas Publs., Mus. Nat. Hist.

Crinnell and Mr. Charles D. Bunker, among others, gave truly valuable en-
couragement and assistance.

Collections containing weasels which were examined in the study here re-
ported upon were as follows:

Acad. Nat. Sciences of Philadelphia
American Mus. Nat. History
Baylor University
Berlin Zoological Museum
Boston Society of Natural History
Brigham Young University
British Museum of Natural History
California Academy of Sciences
Carnegie Museum
Charleston Museum
Coe College
Collection of J. Arnold
Collection of Stanley C. Arthur
Collection of Rollin H. Baker
Collection of William Bebb
Collection of R. H. Coleman
Collection of Ian McTaggart-Cowan
Collection of Stuart Griddle
Collection of John Gushing
Collection of Walter W. Dalquest
Collection of William B. Davis
Collection of J. M. Edson
Collection of Ralph Ellis
Collection of John Fitzgerald, Jr.
Collection of Mr. Green
Collection of Ross Hardy
Collection of Donald V. Hemphill
Collection of L. M. Huey
Collection of R. W. Jackson
Collection of Stanley G. Jewett
Collection of E. J. Koestner
Collection of J. E. Law
Collection of A. H. Miller
Collection of Lloye H. Miller
Collection of R. D. Moore
Collection of J. A. Munro
Collection of O. J. Murie
Collection of Robert T. Orr
Collection of Arthur Peake
Collection of Kenneth Racey
Collection of William B. Richardson
Coll. Rocky Mt. Spotted Fever Lab.
Collection of Victor B. Scheffcr
Collection of William T. Shaw
Collection of O. P. Silliman
Collection of W. E. Snyder
Collection of Frank Stephens
Collection of T. C. Stephens
Collection of D. D. Stone
Collection of Myron H. Swenk
Collection of Joe and Dean Thiriot
Collection of John Tyler

Collection of Jack C vonBloeker

Collection of Alex Walker

Collection of Edward R. Warren

Colorado Museum of Natural History

Charles R. Conner Museum

Cornell University

Donald R. Dickey Collection

Field Museum of Natural History

Florida State Museum

Fresno State Junior College

Humboldt State Teachers College

Illinois Natural History Survey

Iowa State College

Iowa Wesleyan College

Kansas State Agric. College

Leland Stanford Junior University

Leningrad Academy of Science

Los Angeles Mus. Hist. Art and Sci.

Louisiana State University

Mt. Rainier Nat'l Park Collection

Museum of Comparative Zoology

Mus. Polonais d'Hist. Nat., Warsaw

Mus. Vert. Zool., Univ. California

Museum of Zoology, Univ. Michigan

National Museum of Canada

Naturhistorika Ricksmuseum, Sweden

Neuchatel University Museum

New York State Museum

Ohio State Museum

Oklalioma Agric. and Mech. College

Ottawa University, Kansas

Paris Museum

Provincial Museum of British Columbia

Royal Ontario Museum of Zoology

San Diego Society of Natural History

State Hist, and Nat. Hist. Soc. Colo.

State Normal School, Cheney, Wash.

Texas Co-operative Research Collection

United States National Museum

University of Arkansas

Univ. California Mus. Palaeo.

University of Id.iho

Univ. Kansas Mus. Nat. History

University of Minnesota

University of Notre Dame

University of Oklahoma

University of Oregon

University of South Dakota

University of Utah

Univ. Washington Museum of Zoology

University of Wisconsin

Univ. Zool. Mus., Copenhagen

The largest single collection is in the United States National Museum,
where the specimens of the National Museum proper and the United States
Biological Surveys Collection, together, provide essential materials including

Materials, Acknowledgments and Methods 23

a large share of the holotypes. Specimens in all of the North American col-
lections including Canada and Mexico have been made available, by loan, and
in 1937 materials were examined in the principal collections of northern and
central Europe. After the materials in North American collections were as-
sembled, special effort, with considerable success, was made in each of several
winters, to obtain specimens from areas not previously represented in collec-
tions.

To the many persons who were in charge of the collections consulted, to
those who at my request sought critical specimens, and to those who assisted
in various stages of assembling data and in preparation of the manuscript, I
am grateful indeed. Likewise, I am deeply appreciative of the grants-in-aid
received from the Carnegie Institution of Washington, the University of Cali-
fornia Chapter of Sigma Xi, the John Simon Guggenheim Memorial Founda-
tion and the Kansas University Endowment Association. I am mindful also of
an obligation to those who appropriated funds, by legislative action, for re-
search use by The University of California and The University of Kansas.

For assistance with the illustrations I am indebted to the late Major Allan
Brooks for Plate 1, to Mrs. Mary Bios for figures 25-31, to Miss Ann Murray for
figures 11-13, to Mr. W. C. Matthews for all the photographs, to Mrs. Freda L.
Abemathy for figures 2-9, 18-22, 24, and for retouching all the photographs
except the following which were retouched by Mrs. Virginia Unruh: figs, d
of plates 2, 3, 4, 9, 10, 11, 16, 17; figs, i of plates 5, 6, 7; figs, h, j, k of
plate 7; figs. / and g of plates 12 and 13; and figs, c and d of plate 14. To
Mrs. Unruh I am further indebted for figures 1, 16, 17 and 23 and for much
temiinal assistance with preparing most of the illustrations for the engraver.

The methods of study, after specimens were assembled, included
first comparisons of specimens of like age and sex from each of
several localities to ascertain the constant features by which full
species were distinguishable, one from the other. For example, it
was found tliat in every individual from Trout Lake, Washington,
of the species here designated Mustela erminea, the postglenoidal
length of the skull amounted to more than 47 per cent of the
condylobasal length whereas it was less than 47 per cent in all in-
dividuals here designated as Mustela frenata, from the same locality.
Testing of specimens from other localities by means of this and other
selected characters permitted the outlining of the geographic ranges
of the full "species-groups." By comparing specimens of other
nominal species and by examining specimens from localities geo-
graphically intermediate between the nominal species, I found inter-
gradation and therefore arranged the nominal species as subspecies
of a single species. Intergradation here is understood to be the re-
sult of crossbreeding in nature between two kinds of animals in the
area where the geographic ranges of the two kinds meet. Presence
of intergradation between two kinds of weasels was basis for ac-
cording them subspecific rank. Absence of intergradation in nature

24 University of Kansas Publs., Mus. Nat. Hist.

at every place where the geographic ranges of two kinds met or
overlapped, and absence of intergradation by way of some other
kind, or chain of kinds, was basis for according each of the two
kinds full specific rank. By thus applying the test of intergradation,
or lack of it, I found that there were four full species of weasels, of
the subgenus Miistela, in all of the Americas.

Next, the specimens of one species were arranged in trays in a
geographic sequence. The specimens from any one locality were
segregated by sex and under one sex from one place were arranged
from oldest to youngest, that is to say by age. The four series with
the largest numbers of individuals of a given age were selected.
Seventeen cranial measurements and three external measurements
were recorded for each individual of each of these four series. For
each measurement, the coefficient of variation, standard deviation
and probable error were computed. The four samples subjected
to such analysis were a series of adult males, one of adult females,
one of subadult males and one of subadult females. Also, studies
of each sex were made to ascertain seasonal changes in pelage.
After data were obtained on ontogenetic ( age ) variation, secondary
sexual variation, seasonal variation, and degree of individual vari-
ation by studying specimens in the manner described above, tests
were made for subspecific (geographic) variation by comparing
series of specimens of like sex, age and season, from different locali-
ties. For each one of several geographically variable features noted,
a map was prepared for animals of each sex. When all the data
thus obtained were codified, subspecific ranges were, in a sense
automatically, obtained. On the resulting map showing geographic
ranges of subspecies for a species, a type locality was accurately
plotted for each name that had been applied to the species, and
names then were applied in accordance with the international rules
of zoological nomenclature.

VARIATION

Variation with Age

The kind of variation which results from increasing age has been
dealt with extensively for the skull (of the Old World Mustela
erminea) by Hensel (1881) and for the external features and to
some extent for the skull by Hamilton ( 1933) in the North American
forms M. erminea cicognanii and M. frenata noveboracensis.

The young of both erminea and frenata are hairless and blind at
birth. In M. frenata noveboracensis, the eyes open on approxi-
mately the 37th day. When 2 to 4 months old, the tail is pointed

Variation 25

at the tip. This is because the terminal hair of the tail, including
the black tip, is short and lies flat on the tail. In subadults and adults
the hair on the terminal part of the tail is as long as that on the
basal part, and the tail appears to be of uniform diameter all the
way out to the end.

In the western subspecies of M. frenata, and in its tropical sub-
species, animals so young as to have pointed tails commonly have
the underparts of the body more intensely colored than do adults.
The young may have salmon-colored instead of yellowish fur on the
underparts.

Otherwise, in animals that have attained approximately adult
proportions — which appears to be at approximately 6 months of
age in males — there are no variations which are ascribable to in-
creasing age in the color-pattern or pelage that cause the syste-
matist to confuse species or subspecies.

Of the several parts of the skull in juvenal animals, the braincase
and width of the posterior part of the palate are most nearly of the
size attained in the adult, the facial part of the skull at birth is the
least developed, and the interorbital region is, in relation to its ulti-
mate adult size, intermediate in stage of development. The per-
manent teeth are acquired when the animal is approximately eleven
weeks old.

Four age groups, based on characters of the dentition and skull,
have been recognized. They are:

Juvenile. — One or more deciduous (milk) teeth present. Birth to three
months of age.

Young. — Sutures widely open between the maxillae and nasals and between
the premaxillae and nasals. Three to seven and a half months of age.

Subadult. — Sutures between maxillae and nasals visible but indistinct.
Seven and a half to ten months of age.

Adult. — Bones of rostrum coalesced with no traces of sutures visible to the
naked eye. More than ten months old.

The skull as a whole increases in size until the animal is two-thirds
of the way through the stage designated as young. After this time
the width of the rostrum, as measured across the hamular processes
of the lacrimals, increases until approximately a third of the way
through adulthood. The interorbital breadth decreases from late
subadulthood to adulthood and even in adults there appears to be a
slight decrease in this part of the skull with increasing age.

The average zoologist will readily distinguish skulls of juveniles
and young from adults but usually fails to distinguish subadults
from adults. Nevertheless, subadults must be distinguished from
adults if geographic variation is to be measured accurately. The

26 University of Kansas Publs., Mus. Nat. Hist.

reason for this is that such differences in the form (not size) of the
skull as result from increasing age equal and often exceed the differ-
ences of a geographic sort which serve for distinguishing subspecies
that have adjoining geographic ranges. All sutures in the skull,
except those between the tympanic bulla and the braincase, and
those on the dorsal face of the rostrum, are obliterated while the ani-
mal is a subadult. Most kinds of mammals retain sutures throughout
life or until the animals are well into adulthood. Therefore, skulls of
weasels offer fewer features for estimating age than do those of
most mammals and the skulls of weasels that are subadults or older
are more difficult to classify accurately as to age than are the skulls
of most other mammals. More reliance on shape of entire skull and
less reliance on extent and shape of any individual bone is necessary
in estimating the age of a weasel. Wright (1947:344) shows that
the weight of the baculum (os penis) is a certain means of differ-
entiating adults from males of lesser age. When approximately
eleven months old, Mustela frenata oribasus of western Montana
molts from the white winter coat into the brown summer coat. At
that time spermatogenesis starts for the first time and the weight
of the baculum increases from less than 30 milligrams to more than
52 milligrams.

In the autumn and early winter, most of the specimens are sub-
adults. Ordinarily the few adults obtained in these seasons can
easily be segregated from the subadults because ontogenetic de-
velopment in the twelve additional months of life of each of the
older animals has obliterated the sutures on the rostrum, heightened
( vertically ) and lengthened ( anteriorly ) the sagittal crest, widened
the rostrum, and produced still other changes in form that are re-
vealed by direct comparison of specimens of the two ages.

Secondary Sexual Variation

The secondary sexual variation, which has been detected, is in
size of the animal, relative length of the tail and shape of the skull.
The female is the smaller. In the small Mustela rixosa and appar-
ently in Mustela africana the secondary sexual difference in size is
relatively slight. In Mustela frenata and Mustela erminea, males
are approximately twice as heavy as females, the degree of differ-
ence very definitely depending upon the subspecies. For example,
in M. e. richardsonii the recorded weights are 175 and 69 grams as
opposed to 81 and 54 grams in M. e. cicognanii. In general, within
one species the greatest difference in size of males and females is
in those subspecies in which the animals are of large size. The
secondary sexual variation in size is much more than the individual

Variation 27

variation in either sex. The same is not true of secondary sexual
difference in length of the tail (relative to the length of the head
and body), which in eighteen subspecies of M. erminea is from
1 to 7 per cent longer in males than in females. In two subspecies,
A/, e. haidarum and M. e. ohjmpica, the tail is a fraction of a per
cent the longer in females if we may rely upon the few specimens
for which collectors' measurements are available.

In both M. erminea and M. frenata the skull of the female is ap-
proximately 45 per cent lighter than that of the male, or put in the
opposite way, the skull of the male is 83 per cent heavier than the
skull of the female. The difference in this respect varies greatly
depending on the subspecies. For example, the skull of the male
is 127 per cent heavier than that of the female in M. e. richardsonii
but only 33 per cent heavier in M. e. anguinae. In Mustela frenata,
the subspecies noveboracensis shows most sexual dimorphism in
weight of skull (3.6 and 1.7 grams) and olivacea the least (5.3 and
3.8 grams). In general, the difference in this respect is less in sub-
species the individuals of which are of small size.

Therefore, as might be expected, the secondary sexual variation
in weight of the skull is less in M. rixosa, individuals of which are of
small size, than in M . erminea or than in M. frenata, in general of
larger size. Nevertheless, in M. africana, in which the individuals
are of large size, there appears to be less sexual dimorphism in
weight of the skull than in M. frenata or than in M. erminea, al-
though it should be remarked that there are too few data for M.
africana to allow of forming a trustworthy conclusion concerning
the amount of secondary sexual variation in that species.

The secondary sexual variation in shape of the skull consists of a
slenderness in the female. In relation to the basilar length the
spread of the zygomatic arches is more in males and, except in the
one subspecies M. /. altifrontalis, the rostrum is broader. Also the
interorbital region is relatively broader in males of most subspecies.
In most subspecies of both M. frenata and M. erminea the tympanic
bullae are relatively (to the basilar length) longer in females. The
maximum sexual dimorphism occurs in M. erminea arctica and the
minimum dimorphism in M. e. haidarum, M. e. anguinae and M. e.
muricus. Taking into account all of the subspecies of each of the
North American species, the shape of the skull differs most in M.
erminea and least in M. frenata. In the latter species the greatest
difference in shape of the skull, as was true also of its weight, is in
the subspecies M. f. noveboracensis. In these two subspecies, M. /.
noveboracensis and M. e. arctica, in addition to the secondary sexual
variation already mentioned in the skull, females have the braincase

28 University of Kansas Publs., Mus. Nat. Hist.

smoother and more rounded, the postorbital-, mastoid-, and lacrimal-
processes relatively smaller, and the ventral face of the tympanic
bulla at its anterior margin more nearly flush with the floor of the
braincase.

In the weasels, subgenus Mustela, the disparity in size of the two
sexes is almost or quite as much as in any other fissiped carnivore.
It is because of this large degree of difference that the skulls of the
two sexes are described separately in the following systematic ac-
counts. The need for such treatment was recognized by Reinhold
Hensel (1881:127) more than sixty years ago when he wrote in the
introduction to his "Craniologische Studien", of Mustela, as follows:
". . . die Geschlechtsdifferenzen am Schadel vieler Sauge-
thiere ... so gross sind, dass man diese wie schadel ver-
schiedener species behandeln muss, wahrend in anderen Ordnungen
(Rosores, Edentaten) die Schadel solche Unterschiede nichtzeigen."
In the past, failure to appreciate the large amount of secondary
sexual variation has resulted in erroneous deductions as regards
characters of certain geographic races and has been the cause of
some nomenclatural confusion, as for example, in Mustela frenata
macrura, where the female was named as a separate species ( Mus-
tela jelskii ) .

Individual Variation

Individual variation is here considered to be the variation in one
species which can occur between offspring of a single pair of par-
ents, after variation ascribable to differences in age, sex, and season
is excluded. Individual variation, therefore, is a term here used
in a composite sense; it includes variations which probably repre-
sent different genetic strains within certain populations and varia-
tions induced within one generation by environmental factors.

In skulls of weasels, the individual variation in size is more than
it is in relative proportions. Hensel (op. cit.) has stressed that
weasels, like other carnivores, produced "dwarfed" individuals more
than do herbivorous mammals. I cannot vouch for the accuracy of
this view, but can say that individual variation is not greater than
in some other fissiped carnivores. Impressions to the contrary prob-
ably result largely from failure to recognize age-variation. When
skulls of a large series from any one locality are arranged first h\
sex, and under each sex according to probable age on the basis of
extension anteriorly of the sagittal crest and of degree of postorbital
constriction, individual variation is seen to be less than a cursory
examination, even of only one sex, would suggest.

Variation 29

Study of a large series of one age of one sex of one species from
one locality shows that some parts, of the skull for example, vary
more than other parts. In illustration, among 22 male topotypes
of Mustela frenata washingtoni the least interorbital breadth varied
25 per cent (9.0 mm. to 12 mm.) whereas the length of the tooth-
rows varied only 13.3 per cent ( 15.6 mm. to 18.0 mm. ). In color the
individual variation definitely is more in areas of intergradation be-
tween subspecies than in other areas. Details of one such instance
of intergradation are given in the account of Mustela frenata spadix.

Statements to the effect that there is much individual variation in
the color of weasels, were made mostly fifty years or so ago by
writers who had but few specimens from widely separated localities.
Where marked climatic differences exist between localities only a
few miles apart, marked differences occur in coloration of the
weasels from the different localities. Much of what formerly was
mistaken for individual variation now proves to be geographic
variation. Individual variation actually is of slight amount in com-
parison with that in mammals generally. Differences in size and
relative proportions of parts usually are correlated with geographic
differences in color. The color does fade slightly in the period
between molts. Also as a result of the seasonal color change, in
autumn along the upper margin of the Austral Life-zone, some in-
dividuals become white whereas others become white on only the
underparts, the upper parts changing only to lighter brown. Prob-
ably it would be correct to say that this variation was a combination
of seasonal and individual variation rather than either one alone.

As might be supposed, individual variation is not the same in all
species or subspecies. For example, p2 is always absent in Mustela
africana and always present in certain subspecies of M. frenata.
In some other subspecies of M. frenata, p2 is absent approximately
as often as present. In the writer's experience, when only a few
specimens are available for comparison, individual variation is more
difficult to distinguish from specific and subspecific (geographic)
variation than is age-variation or secondary sexual variation.

Among the larger series of specimens examined, only one instance
of what might be called a mutation in the old sense of a large,
sudden change, was detected. That was the loss of the second
lower molar in many (less than a third) of the specimens from
Newfoundland. The six instances of abnormal coloration described
on pages 41 to 43, might be regarded as mutations of large magni-
tude but no evidence was found of repetition of an abnormality in

30 University of Kansas Publs., Mus. Nat, Hist.

any one population. Otherwise, in every instance where plotted,
the manifestations of a variation arranged themselves about the
mean in such a way as to form a smooth, unimodal curve.

Seasonal Variation

When subspecific and specific variations are the objectives of
study, seasonal variation must be understood, in order to be ex-
cluded from consideration, in the same way that variations ascrib-
able to age, sex and individualism must be understood in order to
be excluded from consideration. In weasels, change in color of the
pelage is the seasonal variation most important for the systematist
to understand. Other seasonal variations in the pelage are hairiness
versus nakedness of the pads of the feet, length of the pelage on the
body, and possibly the density of the pelage on the body. In the
northern half of North America, roughly speaking, seasonal change
in color is so pronounced (white in winter and brown in summer)
as to be easily recognized. South of this area, in the Austral and
Sonoran life-zones, the color of the winter pelage differs only slightly
from that of the summer pelage. In these more southern latitudes
the winter pelage in almost all subspecies is of lighter color than the
summer pelage and has a smoky suffusion. With material of the
two seasons in hand for comparison, close attention to the variation
will permit the systematist to recognize the difference in shade of
brown as seasonal variation and not geographic or specific variation.
Farther south still, in the Tropical Life-zone, seasonal difference in
color was not detected in the material studied. Seasonal change
in color is discussed in the section immediately following.

Variation in Coloration, and Molt

In all American weasels (subgenus Mustela) the color, at least
in summer, is brown with more or less white or whitish on the
underparts. In one species, Mustela africana, there is a longi-
tudinal stripe of brown on the middle of the light-colored under-
parts; this stripe is absent in each of the other three American
species. Two species, M. erminea and M. frenata, always have
a black tip on the tail. Of the other two species, M. africana lacks
the black tip and M. rixosa may or may not have a few black
hairs in the tip of its tail. White or light yellowish facial mark-
ings occur in subspecies of M. frenata from the southwestern United
States to Central America. Subspecies having the most extensive
light-colored facial markings have the remainder of the upper
part of the head black. In weasels without light facial mark-

Variation 31

ings the upper parts of the head all are brown. In the two species,
M. erminea and M. frenata, the extent to which the light color of
the underparts extends down the insides of the legs and out on
the underside of the tail, or the absence of light color on these
parts, is a matter of geographic variation. The same can be said
for M. rixosa except that first its tail is unicolored and second in-
dividual variation as well as geographic variation accounts for
the color pattern on the underparts and legs in animals from the
southeastern part of the range of the species.

The most remarkable feature of the coloration of weasels is the
winter whitening. This occurs in the northern part of North
America in each of the three species of weasels found on that
continent. The black tip of the tail in M. erminea and M. frenata
remains black in winter. If an individual of M. rixosa has black
hairs on the tip of its tail in summer, there are thought to be
black hairs there also in winter. Otherwise the winter pelage is
all white in northern areas in each of the three species. In this
white winter coat the animal is known as ermine.

The underlying cause seems to be protective coloration. At any
rate, weasels are always white in winter if they are from areas
where snow lies on the ground all winter, every winter, or al-
most every winter; and they are always brown if from areas where
there is never, or rarely, snow in winter. The changes in color
are effected by molt, one in autumn and one in spring. Animals
that are brown in winter undergo the same two molts as do those
that are white in winter. The capacity to acquire a white coat or
a brown coat in winter is an hereditary matter just as one man
grows red hair and another grows black hair. In the weasels,
however, all individuals in the north turn white in winter and if
one that was born there is kept through successive winters in the
warmer south where there is no snow, he will still turn white each
winter. A weasel born in a southern area, where all are brown
in winter, molts into a brown (not white) winter coat even when
kept in a cold, snowy, northern area where native weasels of the
same species all turn white. Obviously, therefore, neither snow
nor temperature is an immediate cause and, as we have said, the
color in winter is a matter of heredity. The time of the molt, we
now know, is determined by the amount of light. When nights
grow longer and days shorter, a point is reached at which the
lesser light received through the eyes causes the pituitary gland
to cease producing a gonadotropic hormone. Directly or in-

32 Univei^ity of Kansas Publs., Mus. Nat. Hist.

directly, the lack of this hormone stimulates molt and, probably
enzyme action, or the lack of it, causes the melanoblasts of the
cells in the hair follicle to be without pigment. Hence the hair
grown from a follicle under such conditions lacks pigment (mel-
anin) and is white. In spring, as the days grow longer and the
nights shorter, the increasing amount of light received day by
day through the eyes stimulates the pituitary gland to produce
the gonadotropic hormone which directly or indirectly, stimulates
molt and, probably by enzyme action, the melanoblasts are caused
to be present in cells of the hair follicle and the melanoblasts pro-
vide granules of melanin pigment which are incorporated in cells of
the growing hair. These granules of pigment give the hair its
color.

Evidence in support of this hypothesis is given below.

Along the Pacific Coast from British Columbia southward, M.
erminea ( see fig. 25 on page 95 ) is brown in winter. This is an area
where snow rarely falls and the temperature in winter ordinarily
is above freezing. In the remaining part of the American range
of this species the temperature in winter is below freezing much
of the time and snow remains throughout the winter or for long
periods. In this colder part of the animal's range, only white coats
occur in winter. M. frenata likewise has a white coat in winter
in the part of its geographic range where snow and freezing tem-
peratm-es prevail throughout most of the winter and a brown coat
in warmer, snowless areas to the southward and along the Pacific
Coast. The third species, M, rixosa, exhibits a corresponding cor-
relation between coat color and climate. On the Asiatic conti-
nent, several species, including M. erminea, provide parallel
correlations and nowhere are there any exceptions for the sub-
genus Mustela. These data are an important part of the material
on which we have based the induction that the underlying cause
of seasonal change in color is a need for protective coloration.

As regards molt, most naturalists who have written upon the sub-
ject regard it as responsible for the change from the white winter
coat to the brown summer coat. However, the change from brown
summer coat to white winter coat has been thought by several
writers to be effected by change in coloration of the individual hairs.
Among those holding this opinion there may be cited Bell (1874:
197) in reference to Mustela erminea, and Coues (1877:123) in
reference to American specimens to which he applied the same
name. More lately Hadwen (1929) has taken this same view, and
Gunn (1932) also discusses the possibility of the hairs changing

Variation 33

color. Bachman (1839:228-232), MacgiUivary (1843?:158), Au-
dubon and Bachman (1851 (vol. 2):62), Schwalbe (1893:538),
Pearson et at. (1913:447), Miller (1930, 1931A), Hamilton (1933:
300) and Rothschild (1942), among others, have been inchned to
the opinion, or positively affirm, that the color change in autumn
is the result of a molt. The papers cited above contain, in turn,
references to many other printed accounts deahng with this ques-
tion.

To my mind, it has not so far been demonstrated tliat the change
in color of weasels in autumn is accomplished without a molt.
Also so far as I am aware, no explanation has been given of how
the pigment may disappear from the hair of weasels. Metchni-
koflf's (1901:156) idea that the senile whitening of the hair in man
is accomplished by phagocytes which remove the pigment granules
would hardly seem to explain the relatively sudden and complete
autumnal change occurring in weasels. Anyhow, Danforth (1925:
108 ) , and some other students have thought that the action of these
phagocytes was at most a factor of sHght importance in the whiten-
ing of hair. Whatever be the complete answer to the question of
how the weasel changes color in autumn, at least one specimen of
long-tailed weasel, which is in process of color change in autumn,
presents clear evidence of molt of the overhairs. This specimen of
M. f. longicauda is no. 188408, U. S. Nat. Mus., taken on November
12, 1897, at Rapid City, South Dakota. Other specimens of M.
erminea which were taken in autumn similarly show molt to be in
progress. For these and other reasons, I am inclined to the opinion
that die autumnal change in color, like the one in spring, is effected
by molt. During the period of the autumnal color change, Noback
(1935:27) had a captive M. /. noveboracensis and, each morning,
found clumps of brown hair on the floor of its cage; tliis was strong
indication that molt was responsible for the color change in this
instance.

However, I freely admit that the evidence does not prove that
the change from brown to white can be accomplished onhj by
molt; in the present state of knowledge it would be unscientific to
deny that the change were possible of accomplishment by other
means. Also, it is true that the fifteen specimens before me of
Mustela frenata, subspecies included, in process of change from
brown to white, with the exception of the one from Raf)id City,
South Dakota, if taken individually, do not, in macroscopic exami-
nation, show definite molt lines or other absolutely convincing evi-
dence of molt. However, these same specimens, insofar as examined
2—3758

34 University of Kansas Publs., Mus. Nat. Hist.

microscopically, do show overhairs all white, or overhairs pig-
mented throughout. The lighter color of the proximal parts of the
overhairs in itself should not be accepted as evidence of color
change, for in the fresh summer pelage, the same condition exists.
Also, careful macroscopic examination suffices to show that in the
transitional pelage of autumn, the brown overhairs generally are
longer than the intermixed white overhairs.

Whether the underfur behaves in exactly the same way as the
overhair, I have not myself definitely ascertained, but I assume that
the underfur is molted twice each year, at least in the northern
populations of Mtistela frenata and in the other species of more
northern distribution. Schwalbe's (1893) work, including section-
ing of the skin and study of the hair follicles, led him to conclude
that the underfur was molted twice each year in Mtistela erminea.

In Mustela frenata noveboracensis, M. f. nevadensis, and M. f.
nigriatiris, measurements taken on adult males show the overhairs to
be longer in the winter pelage than in the summer pelage of speci-
mens from the same locality. For example, in M. /. nigriatiris irony
Berkeley, California, the overhairs of the summer coat (July and
August) average 8 millimeters in length on the hinder back and
7 mm. on the belly, but average 9.5 mm. and 8 mm. respectively in
January-taken specimens possessing the full winter coat. At Ann
Arbor, Michigan, in the summer coat, the longest hairs on the
hinder back average approximately 12 mm., and those on the belly,
9.5 mm., against 13 mm. and 9.5 mm. respectively in winter. Al-
though general observations initially led me to believe that the
black, terminal hairs of the tip of the tail are longer in the winter
pelage than in the summer pelage, actual measurements fail to
show a difference in length.

The change from one coat to the other in the long-tailed weasel
has been described among others by Miller (1930, 1931A), Hamil-
ton (1933) and Glover (1942) on the basis of captive specimens.
In a general way, the progress of the molt in their specimens agrees
with that which I have been able to make out from examination of
skins taken in the wild. There is, however, this difference: Their
specimens show a more spotted pattern when in process of hair-
change than do specimens taken in the wild. Probably the more or
less unnatural conditions under which these captive animals lived
modified the normal progress of molt.

In wild-taken specimens of the species Mustela frenata, sub-
species included, the spring molt begins on the middorsal line and
proceeds laterally, producing, at almost any given time, a relatively

Variation 35

sharp molt line separating the white winter hair from the incoming
brown summer coat. However, in autumn the change takes place
first on the belly, then on the sides, and finally makes its appearance
over all the upper parts at about the same time, with the result that
the upper parts have a salt-and-pepper appearance without at this
time any sharply defined molt Hnes. In general, the molt pattern
can be said to be reversed in the two seasons; in spring, it begins
on the back and in autumn, on the belly. The difiFerence in spring
and autumn color pattern is better illustrated on plate 39 than by
additional description. Swanson and Fryklund (1935:123) have
observed that the "spring molt proceeds differently" than the fall
one in Mustela rixosa, and Barrett-Hamilton (1903:309) in com-
menting on the European hare (and the stoat?) remarks, "In spring
the moult, and with it the brown colour, progresses in exactly the
opposite order . . ." as compared with the white color of au-
tumn, which that particular writer thought resulted from removal
of pigment from the hairs rather than from molt.

The tail, excepting the black tip, lags in the molt in many in-
stances, with the result that, especially in spring, it may retain a few
white hairs as late as does the belly. In autumn it is less tardy and
so far as I have observed, becomes white at about the same time
that the general area of the back changes color. On the tail, the
black tip itself, as clearly shown in more than a score of specimens,
is molted at approximately the same time in autumn as is the pelage
of the body. However, the long black hairs, which appear in, say,
November, appear to increase in length until January. In spring,
the long black hairs of the tip of the tail seem not to be shed at
the same time as the rest of the winter pelage, but remain approxi-
mately six weeks longer and then are replaced by long black hairs
of the summer coat. At any rate, this is the picture presented by a
half dozen specimens of M. /. nevadensis and M. f. longicauda
which do show a spring molt to be in progress on the black tip of
the tail. Schwalbe similarly (1893:536-537) has suggested that
the black tip of the tail in Mustela erminea in spring is not molted
until about two months after the pelage on the rest of the body is
changed. Schwalbe {he. eit.) thinks also that in M. erminea
studied by him, the black tip of the tail in autumn is replaced ap-
proximately one month in advance of the pelage on the rest of the
body. As indicated above, my specimens of Mustela frenata, sub-
species longicauda and nevadensis, do not show this discrepancy in
autumn. I have considered the possibility that the black tip of the
tail, in some species of Mustela, is molted only once while the re-

36 University of Kansas Publs., Mus. Nat. Hist.

mainder of the coat was undergoing two molts. My inconclusive
data lend but little support to this possibility.

The difFerence in pattern of color between specimens taken in
autumn and spring is known to some fur-trappers of my acquaint-
ance who have suggested that molt occurs in spring, whereas the
individual hairs change color in autumn. Reference to plate 39 wall
show how gross comparisons might lead one to this erroneous ex-
planation of the color change.

As to time of molt: In eight subspecies of Mustela frenata,
namely, noveboracensis, occisor, primulina, spadix, longicauda, ari-
zonensis, nevadensis and effera, material is available to indicate that
the autumnal molt begins in October and is completed in Novem-
ber, and that the spring molt occurs in March or April. A con-
densed list of specimens providing basis for this statement is as
follows :

M. f. noveboracensis: 26 specimens in transitional pelage taken in auttunn
and 14 taken in spring; M. /. occisor: One topotype has acquired one-fifth of
the winter pelage on October 22, 1896; M. /. primulina: 2 in November, one
in March, and 2 in April are in process of change; M. /. spadix: 6 autumnal
specimens and one in April show pelage change; M. /. longicauda: 7 autumnal
specimens and one in April show pelage change; M. f. arizonensis: 12 speci-
mens in autumn and 3 in spring are in process of molt; M. /. effera: One No-
vember-taken male has acquired four-fifths of the winter coat and another
taken on April 21 at Fort Rock, Oregon, is half finished with the spring molt.

It may be added that no marked difference in time of either au-
tumnal or spring molt is apparent as between the more northern and
more southern localities from which the mentioned specimens come.
With more complete material I would expect to find a difference in
this regard.

The material of the other, more southern, subspecies of Mustela
frenata has not been adequate to show the time of molting or the
number of molts which occur in one year.

Animals in the northern part of the range of Mustela frenata
acquire a white winter coat, whereas those in the southern part
acquire a brown winter coat, and in an intervening area the winter
coat may be either browoi or white. By plotting on a map the locaH-
ties of capture of all specimens examined in the winter coat, it was
possible to outline this intervening area as shown in figure 10 on
page 37. However, Dearborn (1932:36) shows that in Michigan
some animals have a brown coat in winter at places farther north
than figure 10 shows to be the case. Hamilton's (1933-306) map
for New York shows the same to be true in that state. Accordingly,
the boundaries of the area shown in figure 10, in which both brown

Variation

37

ec M

Fig. 10. Map showing the region (in black) where both the brown and white
winter pelage is found in the long-tailed weasel, Mustela frenata.

and white long-tailed weasels occur in winter, are known to be
only approximate; with full information available the belt would be
represented as wider.

Hamilton (1933:302) has pointed out that "Where half of the
weasels remain brown, these brown winter specimens are always

38 University of Kansas Publs., Mus. Nat. Hist.

males." The results of my own examination of specimens not
studied by Hamilton, in a general way provide confirmatory data.
More exactly, my examination reveals that at the most northern
localities where brown specimens occur, only males are in this
coat. In explanation, it may be said that in plotting on a map locali-
ties of capture of specimens in the winter coat, thirteen places were
found where both sexes were represented and where both brown
and white winter coats were found. With the two sexes, it is
theoretically possible to have nine diflFerent combinations of coat
color. With males all brown, there might occur females (1) all
brown, (2) all white, or (3) some brown and some white. In ad-
dition to these three combinations, we might have three more by
finding the mentioned types of female coat color repeated where
all males are white, and three more, or nine in all, by substituting
a population of males some of which were brown and some of which
were white. Seven of these possible combinations actually were
found. The two combinations not found were all white males with
all brown females, and all white males with females both brown
and white. In the three instances where the males all were brown
and the females all were white, the localities of capture were in the
northern part of the variable area. This indicates that where the
brown winter coat occurs at northern localities, the brown indi-
viduals are all males. Farther south, of course, the females, too,
acquire the brown winter coat.

Stated in another way, there is a broad belt across North Amer-
ica from the Atlantic to the Pacific in which males of Mustela frenata
at any one locality may be either brown or white in winter. Inside
this broad belt there is a narrower one, approximately half as wdde,
in which females at any one locality may be either brown or white.

In support of the idea that color of the winter coat is an hereditary
matter and that it is not dependent on temperature, the following
evidence derived from my transplanting specimens of Mustela
frenata supports the idea that color of the winter pelage is de-
pendent on heredity and not on temperature or snowfall.

A male captured on June 24, 1937, in the brown summer coat in
Salt Lake City, Utah, was received by me at Berkeley, California,
five days later and kept in captivity almost six months. On No-
vember 17, 1937, half the pelage was white and on December 27,
1937, when next examined, the animal was in the full, white, winter
coat as it was on January 25, 1938, when it died. Native weasels
all turn white in winter in Salt Lake City, but in Berkeley native
weasels always are brown in winter.

Variation 39

A juvenile or young animal, a male, captured in May, 1936, at
Lafayette, Contra Costa County, California, was kept there until
August 13, 1936, when transferred to Calneva at the north end of
Lake Tahoe, California. The weasel was kept at Calneva until its
death on December 23, 1937. In both the winter of 1936-'37 and
in that of 1937-'38, the winter coat was brown as in animals from
its place of origin ( Contra Costa County ) and unlike weasels of the
Tahoe region nearly all of which turn white in winter.

Two females, each approximately two months old, captured on
May 1, 1936, at James Landing, 4 miles northwest of San Pablo,
Contra Costa County, California, were kept in Berkeley, California,
until August 13, 1936, when they were transferred to the mouth of
Blackwood Creek, on tlie west side of Lake Tahoe, California. On
October 25, 1936, both weasels escaped. On December 25, 1936,
the headless body of one of these was found approximately 300
yards soutli of the mouth of Blackwood Creek. The animal had
been dead at most a few days when found and was in the brown
winter coat. At the place of its origin all weasels are brown in
wanter but at the mouth of Blackwood Creek only 2 of 60 weasels
caught there in the winter coat were brown; the other 58 were white.
The headless weasel was identified, as one of the two formerly in
captivity, by means of certain short toes, the ends of which had
been clipped off when the animal was a captive. No trace of the
second female was found.

A female of unknown age, in white winter pelage, captured 4
miles southeast of Tahoe City, California, and kept there until April
3, 1937, on which date it was brought to Berkeley, California, molted
to brown in the spring. The first signs of the brown coat were
noted on April 14. On May 24 or 25 she gave birth to 4 young
which lived less than ten days. In the following winter this animal
acquired a white coat. As previously noted, weasels native to the
Berkeley area, where this female was kept, have brown coats in
winter.

The weasels were in every instance kept in cages out-of-doors.
The sides of the cages were open to the elements. A nest box in
each cage provided shelter. All were of the species Mustela
frenata.

The significant results, it seemed to me, were that the winter
coat was the kind found in the area where the weasel originated
instead of the kind found in weasels native to the areas in which
the specimens were held in captivity.

40 University of Kansas Publs., Mus. Nat. Hist.

That the time of molt is determined by the amount of light has
clearly been shown by Bissonnette (1944:223) for American weasels
of the two species Mustela erminea and M. frenata. In his words
{op. cit.:2A6) "Reducing the daily periods of light induced molting
and regrowth of new fur. ... In the Bonaparte weasels [Mus-
tela erminea], white replaced brown. . . . Increasing daily
light-periods caused molting and change to dark brown. . . .
Incomplete molts in both directions ( toward white or toward brown )
were produced as a result of early reversal of increase or decrease
of daily light-time. . . . That this stimulus is received through
the eyes and acts through the anterior pituitary gland is indicated
by Bissonnette's [1935:159] studies on ferrets, a nearly related
animal. That the thyroids and sex-glands are not essential is at
least suggested ... by Lyman's (1942) study on the varying
hare [Lepus americanus]." It can be added that Lyman (1943:
451) demonstrated in Lepus americanus that the effect of light is
received through the eyes. He demonstrated this by masking the
animals. To Wright (1942B:109) who studied the two American
weasels, M. erminea and M. frenata, it seemed likely that the pitui-
tary produced or released gonadotropic hormone at about the
time of the spring molt and that this molt and the spring changes
in the reproductive tracts of the weasels might be caused by a
stimulus from a common source. Later, Wright (1950:130) in-
jected a gonadotropic hormone into long-tailed weasels which
had recently acquired their white winter pelage and thereby
caused them to lose the white pelage and acquire the brown
pelage. It is Lyman (1943:450) who says, in relation to Lepus
americanus, "When in the physiologically white condition, the
melanoblasts of the regenerating guard- and pile-hair folUcles con-
tain no melanin-forming enzyme (dopaoxidase), which may be the
reason for the lack of pigment." Schwalbe (1893) by sectioning
the skin and microscopically examining the hair-follicles of M.
erminea learned that the basal cells producing hairs lacked pigment
granules in autumn when the European ermine (M. erminea) was
acquiring its white winter coat and that tlie cells contained granules
of pigment in spring when, as we know, the granules are incorpo-
rated in the growing hair and give it its color.

The above material, then, is basis for the account on pages 31
and 32 of what causes the weasel of northern areas to have a white
coat in winter. The discerning student will instantly perceive that
although some parts of the account on pages 31 and 32 are pre-
cisely accurate, other parts are the result of inferences which need

Variation 41

to be proved. More careful work of the kind that Schwalbe (1893)
and Wright ( 1942B ) did is needed. The account on pages 31 and
32 is merely the best that can be given with the information now
available.

Many writers have commented on the yellowish color, sometimes
with a greenish tinge, found on the fur of weasels in the white
winter coat. The stain is more often found on the tail and hinder-
parts of the body than elsewhere. Possibly, partly on this account,
some have ascribed tliis color to the smearing of the fur with urine.
Still others have thought it resulted from the smearing of the fur
with secretions from the anal scent glands. Schumacher ( 1928 )
takes this point of view, and while it may be that he has not proved
his point, still his conclusions fit the known facts and seem sound
to me. Schumacher points out that the same soiling of the fur is
present in summer as well as in winter, but that on the summer
pelage the stain can be detected only on the Light-colored under-
parts. It is from this point of view that he criticizes the systematic
worth of white versus yellowish-white underparts in the summer
pelage of geographic races of Miistela erminea and Mustela nivalis.
Although in the long-tailed weasels (Mustela frenata) the under-
parts of all the races are pigmented with some form of red, orange
or yellow, it seems probable to me that the additional color resulting
from the soiling effect of this glandular secretion explains the greater
variation, found at a single locality, in the color of underparts than
of upper parts in the summer pelage.

I have neither seen nor heard of a black weasel in any part of
the New World or of the Old World. I have found only one albino
among American specimens. It is an adult female, no. 121424,
American Museum of Natural History, of Mustela erminea richard-
sonii, taken on August 30, 1935, at Hot Springs, Northwest Territory.
This place, I am told by G. G. Goodwin who obtained the animal,
is on the "Nahanni River where the rugged mountain ridges rise
abruptly from the low mud flat lands, latitude 61, longitude 125."
The shortness and coarseness of the hair corresponds to that of the
summer pelage and not winter pelage. The pelage is everywhere
white, even the tip of the tail. True, all except the nape and top
and sides of the head has a faint yellowish-green tinge which has
been supposed to result from staining by secretion of the anal scent
glands but there is no pigment in the hair as in erythristic specimens.
From the Old World, Farurick (1873:17) has recorded what he re-
gards as an albino of Mustela vulgaris since it had no black hairs
on the tip of its tail. Flintoff (1935:228, 229) records what may

42 University of Kansas Publs., Mus. Nat. Hist.

have been an albino Mustela vulgaris from Yorkshire and an albino
M. crminea from an unstated locality. Jackel (1873:459) mentions
specimens of Mustela erininea and Mustela vulgaris, which were
partly "albinistic" or "erythristic." Among the American specimens
of M. erminea I have not recorded any which appeared to be either
partly or wholly erytliristic or only partly albinistic. Among the
1550 skins of M. frenata which were in summer pelage or browoa
winter pelage, five, described below, show marked abnormalities in
color.

Two of these five are partly albinistic. One is an adult male, no.
223880, U. S. Nat. Mus., from Billy's Island, Okefinokee Swamp,
Georgia, which has the nose as well as the area between the eyes
white. Also there is a tuft of white hairs at the anterodorsal margin
of each ear, scattering white hairs suggesting a postorbital bar on
each side of the head, and a patch of white hairs on the middorsal
line behind the ears. Markings of this kind are not abnormal in
M. f. periinsulae, the subspecies adjoining on the south, except for
the white nose which clearly is an instance of partial albinism. The
second specimen is a subadult male, of M. /. noveboracensis, no.
177679, U. S. Nat. Mus., in process of acquiring the brown winter
coat, taken on November 27, 1911, at Gaylordsville, Connecticut.
It has white markings on the nose, on the right side of the neck, on
the right hind foot and right forefoot, and on the tip of the tail.
The white area of the nose on the left side extends back to the
eye, but on the right side barely encircles the nose-pad. On the
right side of the neck, all that area between the foreleg and ear is
white from the mid-dorsal line (including 7 or 8 millimeters to the
left of the mid-dorsal line) down to the throat, which is white as
it is also in normal individuals. The toes of the right hind foot are
more extensively white than in normal specimens of noveboracensis,
and all of the right forefoot as well as the wrist is white. The tail
is of striking appearance because of its tricolor pattern. The proxi-
mal part is of the normal brown color. The black terminal part
commences proximally at the usual place, but the distal 11 milli-
meters of the fleshy part of the tail bear only pure white hairs pro-
ducing a terminal white pencil 35 millimeters long.

The three otlier specimens abnormally colored are erythristic
individuals. An adult male of M. /. latirostra, no. 7574, coll. D. R.
Dickey, taken on April 14, 1918, at Covina, Los Angeles County,
California, has the color of the upper parts greatly restricted, and,
in addition, has spots and blotches of the color of the underparts
distributed over the back and rump. A spot of this same color

Variation 43

occurs above each ear. Incidentally, this and other subspecies of
Mustela jrenata from the Pacific Coast of North America obviously
have the factor for erythrism operating over a larger part of the
body than it does in M. erminea or than in M. f. noveboracensis,
where the underparts sometimes are white. In M. f. latirostra and
in other subspecies from the Pacific Coast the light color of the
underparts always is tinged with this reddish color.

Another erythristic specimen is a young male of M. f. nevadensis,
no. 23493, U. S. Nat. Mus., taken on August 6, 1890, at Birch Creek,
Idaho. It has all of each foreleg, the axillary regions, and a saddle-
shaped area over the shoulders of the same buff-yellow color as the
underparts.

The third erythristic specimen is a subadult female, of M. f. ore-
gonensis, no. 47149, Mus. Vert. Zool., taken on December 20, 1930,
at Carlotta, Humboldt County, California. This specimen appears
to be white and initially was thought to be merely an individual in
the white winter coat. Closer examination, however, shows that
it has a light wash of ochraceous or faint reddish color. Also, other
specimens taken in winter at Carlotta show that weasels there do
not acquire a white winter coat. The only normally brown area is
approximately three millimeters in diameter at the anterodorsal
margin of the pinna of the right ear. The tip of the tail is black as
in a normal specimen. The specimen in question is actually pure
white only on top of the head from a short distance behind the ears
on over the forehead nearly to the eyes, and on the inside of the
ears. In a normally colored animal this area is the dark area of the
head. In this freak, the other parts of the head, which, in indi-
viduals of normal coloration are the white or light orange facial
markings, have the reddish cast of the remainder of the body, al-
though the color is less intense than on the back. The collector
noted that the specimen had eyes of normal color. A possible
explanation for the coloration of this specimen is that this species
has three factors for color, one for the black tail tip, one for the
reddish color, and a third, missing in the specimen in question, for
the blackish brown.

For some more exact knowledge concerning this erythristic type of
coloration, we are indebted to Pitt (1921:99), who describes a pop-
ulation of polecats, Mustela putoritis, in Cardiganshire, England, in
which this erythristic variation is maintained in a state of nature.
In ferrets, Mustela furo, Pitt {op. cit.-.WA) notes that ", . . ery-
thrism is certainly dependent on a Mendelian factor, being dom-
inant to albinism and recessive to the black-brown coloration. Both

44 University of Kansas Publs., Mus. Nat. Hist,

in the ferret and polecat, erythrism seems to be correlated with in-
creased size, and certainly in the ferret is usually accompanied by
a quick temper and general increase in vitaHty."

Variations of Taxonomic Worth

Variations of taxonomic worth usually are referred to as charac-
ters. For example, shortness of the tympanic bulla is a character,
and the opposite condition, long tympanic bulla, is another char-
acter. Specific variations, that is to say specific characters, are pro-
vided by the color-pattern, length of tail, number of premolar teeth,
shape of the tympanic bullae, and length of the braincase in rela-
tion to the length of the tooth-bearing parts of the skull. Subspecific
characters are provided by color-pattern, color itself, size as meas-
ured by weight of the animal, and its hnear measurements, size of
the skull, and size and shape of parts of the skull. The characters
distinguishing subspecies from one another are not of a different
nature from those distinguishing species from one another.

Given any one of the above structural features, say, dorsal outline
of the skull, several characters may be provided by it. For example,
weasels of tlie species Mustela frenata have the dorsal outline of the
skull convex in southern Louisiana, straight in Missouri and concave
in North Dakota, thus providing three characters. This is geo-
graphic variation. These variations, characters in zoological par-
lance, when plotted on maps, reveal the geographic occurrence of,
say, the convex shape of the skull. Tn combination with other
characters, for example, dark color and short tail, basis is provided
for recognizing a subspecies, in this instance Mustela frenata arthuri
of Louisiana. Because the change from convex to flat skull takes
place geographically at about the same place (in eastern Texas) as
does the change from short tail to long tail, and the change from
dark color to light color, it is easy to draw a line there marking the
western geographic limit of occurrence of the M. f. arthuri. This
same line marks also the eastern margin of the geographic range
of the subspecies Mustela frenata frenata, the subspecies next ad-
jacent to the westward. On this line and for several miles to either
side of it weasels show varying combinations of these three char-
acters or an intermediate condition as regards one or more of the
characters, or both. For example, from a locality in eastern Texas
a weasel may have (1) a facial pattern exactly intermediate be-
tween that of the unicolored face of arthuri and that of the bi-
colored face of frenata, (2) the long tail of frenata and (3) the con-
vex skull of arthuri. In the sum of its characters this specimen is

Variation 45

exactly intermediate between typical arthtiri and typical frenata.
Another specimen from the same place may differ from the first
specimen only in having the tail slightly shorter. The total "score"
for the two specimens is, therefore, by a very slight margin in favor
of arthuri. Let us suppose that we obtain a third specimen from the
same place and that it has the face marked like that of artliuri but
the tail fully as long, and the skull as lacking in dorsal convexity, as
in frenata. Now tlie score is definitely for frenata. For convenience
of handling, the population is referred to frenata, providing that the
average of specimens from a nearby locality to the westward is not
in favor of arthuri. In event the average of specimens from a lo-
cality next adjacent to the westward is in favor of M. f. arthuri, the
total evidence from the two localities may be weighed together and
appropriate decision as to subspecific status of weasels from the
area is made according to what tlie average is for the area as a
whole.

The three individual animals of an intermediate sort are ordi-
narily termed intergrades. This implies that their characters are
the result of mixed parentage — perhaps a female of M. /. arthuri
and a male of M. /. frenata but probably each parent itself was
an intergrade and the offspring, of which we examined three, owe
their characters to reproductive processes operating in obedience
to Mendelian laws of inheritance.

The two kinds of animals, Mustela frenata arthuri and Mustela
frenata frenata, are identified as subspecies because of the inter-
gradation between them. If at this and all other places where
the geographic ranges of arthuri and frenata met there was no
crossbreeding (no intergrades), the two kinds would be treated
as distinct species. Intergradation, and the lack of it, are accepted
as the criteria of subspecies and species, respectively.

These criteria suffice for animals, in this instance weasels, which
have a continuous geographic distribution. Some kinds of weasels
are confined to islands, as for example the islands off the coast
of Alaska and British Columbia. Because weasels are land animals,
crossbreeding in nature between the weasels of two islands is,
of course, impossible. A modified test (used in the study here
reported upon) in deciding on specific versus subspecific status
in these instances can be made as follows: On tlie adjacent main-
land, ascertain the degree of difference between two subspecies
whose geographic ranges meet (for example, M. e. richardsonii and
M. e. alascensis). Next ascertain the degree of difference between
the insular kind of animal and the kind on the mainland. If the

46 University of Kansas Publs., Mus. Nat. Hist.

degree of difference is greater when the insular kind is compared
than when only the kinds of the mainland are compared, tlie insular
kind is to be regarded as a species. If the degree of difference is
no greater between the insular kind and the mainland kind than it
is between the two adjacent mainland kinds, the insular kind is to
be regarded as a subspecies. In short, for insular kinds, the cri-
terion is degree of difference, with the limitation of geographic
adjaceny, rather than intergradation.

The geographic variation ( subspecific characters ) found could be
spoken of as two kinds: First, there is the variation which is ex-
pressed in a general trend for a long distance, producing, in general,
a cline of even slope; and second, that of inconstant trend in any
one direction. In his "The Rabbits of North America" Nelson
(1909:34-35) has commented on the latter type of variation as fol-
lows: "While studying series of specimens from all parts of the vast
range occupied by the geographic races of such species as Sylvilagus
-floridanus and S. auduboni, I have been impressed with evidences
of fluctuation of both external and skull characters. These fluctu-
ations are somewhat wavelike in character and rise to central points
of extreme development and tlien sink away to intermediate borders
beyond which new waves rise. Where the waves of differentiation
are pronounced they mark recognizable geographic races. Within
the area covered by the larger or geographically broader waves of
differentiation (recognized as of subspecific value), smaller waves
of differentiation are included, which may represent local variations
in intensity of characters of the subspecies, or these characters may
diminish and the variation tend in other directions, sometimes even
closely reproducing the characters of another subspecies occupying
a distinct area." In Mustela frenata, much of the geographic varia-
tion at first inspection appears to be of this nature. Closer scrutiny,
however, reveals that the repetition, at geographic intervals, of
several features of color and structure are closely correlated with
environmental features which are repeated only at these same
places.

In Mustela erminea, much of the variation is of the first kind,
namely, that which can be expressed as long clines of relatively even
slope. As several authors have said, zoological classification based
on this kind of variation is like dividing the spectrum and depends
largely upon the standards set, for, theoretically, the possibilities of
subdivision are unlimited. Actually, however, none of the clines
has an even slope and the possibilities for subdivision therefore
are limited. Also, when several features are used, instead of only

Variation 47

one feature, the classification is more satisfactory even if the basis
is more complex.

Some features of structure which provide subspecific characters
are mentioned below.

Total length, of males, ranges from 598 to 360 mm. in M. frenata
and from 336 to 228 mm. in M. erminca. There is no cline of sus-
tained slope in M. frenata but in M. erminea there is a progressive
decrease in total length from north to south.

Length of tail varies from as little as a half to as much as seven-
tenths of the length of the head and body in M. frenata, the sub-
species neomexicana having the long tail and the two subspecies
arthiiri and primuUna having short tails. The geographic ranges of
primttlina and neomexicana are contiguous. In M. erminea there is
likewise no variation of a clinal nature in length of tail and fur-
thermore the variation is much less than in M. frenata.

In length of hind foot, which in males varies from 49 mm. in
northern populations of M. erminea to 28 mm. in southern popula-
tions, the same cline is seen as in the total length of animals of this
species. In M. frenata, however, there are several decreases and
increases along any straight line which can be drawn through the
geographic range of the species. The range of variation in males
is 41 mm. (M. /. arizonensis) to 59 mm. (M. /. macrophonius) .

Weight of the entire animal is an excellent measure of size but
weights are unavailable for many subspecies. In M. frenata, the
two subspecies texensis and macrophonius probably are the heaviest
and effera, arizonensis and helleri probably are the lightest. Geo-
graphically the variation in weight behaves in approximately the
same way as does the measurement of total length. In M. erminea
the variation in weight of males is from 206 grams in northern
animals to 58 grams in southernmost populations, there being a
relatively constant gradient geographically.

Degree of hairiness of tlie foot-soles in M. frenata clearly is linked
with the temperature; in regions of high average temperature the
hairiness is least and in regions of low average temperature it is
most. The decrease in hairiness is accomplished in two ways,
namely, smaller breadth and decreased length of individual hairs
and decrease in number of hairs on a given area of dermal surface.
This correlation holds throughout the entire north to south range
of the species. Corresponding differences are found on the same
latitude where topographic diversity in an east to west direction
produces northern conditions at high altitudes and southern condi-
tions at low altitudes. The conclusion seems unavoidable that

48

University of Kansas Publs., Mus. Nat. Hist.

12

13

Figs. 11-15. Dorsal views of adult skulls of each sex of five subspecies of the
ermine, Mustela erminea, to show secondary sexual variation and geographic
variation in size of the skull. Males on the left and females on the right.
AU XI.

Note especially the geographic variation in decreasing size of the skull from
north to south in each sex, and that the secondary sexual variation in size of
skull is less in ermines with small skulls than in those with large skulls.

Variation

49

140 130 120 110 100 90 80

f Me richardsonii, Ft Franklin, Mackenzie. d",i33847, A M N h.

\

\
• - \

%^

^.

'^

"^

^ M e. richardsonii^ Ft Resolution, Mackenzie. ?, 129703, U.SIM.VI
!

/ i '

I

ip M. e. invicfa, Jasper Park, Al be rtad',3593,?, 10797, CN

/

/

/

-^ 14 / ( ■-- I !

vj§ M e gulosa, Trout Lake, Washington. t?',82i77, ?,77370,uSNivi

I

/

/

:/

I

\

15' T 1--. ^

^ M e muricus. Baker Creek, Nevada. </',4i50i,?,4i502.Mvz.

/ • I s I -i

\ /• / i s ^

\

AL

I

I

?

N

50

40

110

100

90

Fig. 16. Map showing the localities where the skulls, represented in figures

11-15, were obtained.

50 University of Kansas Publs., Mus. Nat. Hist,

climate, directly or indirectly, determines the degree of hairiness.
Less careful observations were made on the hairiness of the soles
of the feet in other species but it is clear that the northern species
M. erminea has the most hair on the foot-soles and that M. africana,
the tropical weasel, has the least. In this regard, M. frenata is
intermediate as it is also in geographic position.

The maximum length of facial and carpal vibrissae is attained in
M. erminea in the far north. In weasels from north of the Arctic
Circle the longest facial vibrissae extend posteriorly beyond the
posterior border of the ear. In the tropical weasel, M. africana, the
facial vibrissae do not extend posteriorly beyond the ear and the
carpal vibrissae are not so long as the distance between their bases
and the apical pad of the first digit. The correlation of long vibris-
sae with low temperature, is mentioned here merely because length
and density of pelage were under consideration.

The most obvious and most exact correlation between change in
climate and change in the animal is furnished by color. This is well
shown in the one species, Mustela frenata, to which the following
remarks apply unless indication is given to .the contrary. The color
of the upper parts varies from bay ( blackish brown ) in M . /. pana-
mcnsis to buckthorn brown (light brown) in M. /. neomexicana.
The color of the head varies from solid brown (white chin ex-
cepted) to contrasting black and white markings.

Dark color of the upper parts is associated with a large area of
this color; the enlargement of this area is at the expense of the area
of light color on the underparts. In the weasels of darkest color
the upper parts occupy four-fifths of the circumference of the body
(as measured in the anterior lumbar region) but in the lightest-
colored weasels the upper parts comprise only two-thirds of the
total circumference. In these light-colored animals the color of the
underparts extends onto the underside of the tail and down the
insides of the legs and over the feet whereas in the animals with the
darkest upper parts tlie entire tail, feet, and legs below the knees
ordinarily are of the same dark color as tiie upper parts. The length
of the black tip on the tail varies inversely with the length of the
tail, probably because the lightest-colored weasel has tiie longest
tail. In some subspecies the black brush is almost half as long as
the tail-vertebrae but in others is less than a fourth as long as the
tail-vertebrae.

The extent of the color of the head, as well as the intensity of the
color there, varies markedly and is correlated with climatic condi-
tions. The extent and intensity of this dark color is greater in

Variation 51

weasels inhabiting regions of heavy rainfall than in those inhabiting
regions of sparse rainfall. Considering the geographic range of
each subspecies of Mustela frenata, that of M. f. panamensis has the
maximum of rainfall. Reference to the colored plate ( 1 ) will show
that in M. f. panamensis ( 2 ) the black of the head is extended over
all of the upper parts. M. f. macrura ( 1 ) of Peru, to the southward,
is from an area of lesser rainfall and is correspondingly lighter col-
ored. Returning to panamensis (2) as a starting point and pro-
ceeding northward to the range of nicaraguae (3), which also has
lesser rainfall, thence another step northward to Guatamala, which
has still less rainfall, the weasel there, M. /. goJdmani (4) has the
black extending posteriorly only to the shoulders. M. /. leucoparia
(5) from Michoacan, and M. /. frenata (6) from Tamaulipas are
from progressively more northern and also progressively drier
regions. In M. f. frenata ( 6 ) the dark color extends posteriorly only
to the ears and is blackish rather than black. In M. /. neomexicana
(7) of the extremely arid parts of Durango, Arizona, and New
Mexico the dark marking of the head is confined to a brown spot on
the nose. Its geographic range is the most arid of those of all of
the subspecies. The contrast between neomexicana (7) and pana-
mensis (2) illustrates the great range of geographic variation in
color which occurs in the one species. Continuing from the geo-
graphic range of neomexicana (specimen from Safford, Arizona)
northwesterly 480 miles to Riverside, California (see 8, latirostra),
430 miles north to Point Reyes, California (see 9, munda), and
finally 570 miles north to Tillamook, Oregon (see 10, altifrontalis) ,
each place with more rainfall than the one farther south, another
correlation of increasingly dark coloration with increasing amount
of rainfall is illustrated.

This geographic variation, it should be remembered, is all within
one species. It is the more significant still when we remember
that the same correlation, with never an exception, occurs at hun-
dreds of places within the geographic range of the species. A
particular feature of climate, namely rainfall, and possibly there-
fore humidity, is concerned in this correlation. The same cor-
relation, heavy rainfall and dark color, is shown also in the other
species of North American weasels. The conclusion is unavoidable
that climate, directly or indirectly, determines or influences the
color of weasels.

The light facial markings appear in American weasels in two
separate geographic areas. One is the southwestern United States,

52 University of Kansas Publs., Mus. Nat. Hist.

Mexico and northern Central America. The second area is in the
same latitude, in Florida and adjoining parts of Georgia and Ala-
bama. In the western weasels the markings are white south of
latitude 32° N. North of this latitude, the facial markings, if at
all extensive, usually are of the same yellowish color as the under-
parts of the body. Weasels of southern California and its interior
valley usually have these yellowish instead of white facial mark-
ings. The light facial markings, in this instance, white markings,
attain their maximum extent in M. /. leucoparia of the southwestern
margin of the tableland of Mexico, at latitude 19° N. A gradual
decrease in area of the light facial markings occurs both to the
north and south; they disappear at 10° N in M. /. costaricensis and
at 35° N at approximately the southern limits of range of M. f.
arizonensis and M . /. nevadensis. In the mild climate of California
the light (yellowish) facial markings are found at still higher lati-
tudes. These light facial markings crop up as vestiginal remnants,
consisting of a few white hairs, in some individuals of nearly all
races of weasels.

In certain parts of the skull there are trends, in size and shape,
which continue for long distances geographically. In other words,
clines can be recognized. Changes in size and shape in some
other parts of the skull are wavelike; change toward narrower
rostrum, for example, is not progressive in a given geographic
direction for any great distance. Length of the upper tooth-rows
and zygomatic breadth, when expressed as percentages of the
basilar length, and also the actual length of individual teeth vary
geographically in the same wavelike fashion as does the width of
the rostrum.

Size of the skull, on the other hand, shows a sustained trend for
a long distance; it becomes progressively smaller from the southern
United States southward to Columbia, South America. This clinal
variation can be demonstrated by plotting on a graph, the basilar
length, the zygomatic breadth, or the weight of the skull. Begin-
ning at Merida, Venezuela, and proceeding southward to increasing
elevations in the mountains of South America, there is a reversal
of the direction of the variation in this cline; weight of skull, for
example, increases to the southward from Merida for a consider-
able distance. A cline of decreasing width of the postorbital con-
striction of the skull is evident from Panama north into Texas.

Variations in the tympanic bullae provide many characters use-
ful in distinguishing weasels from different localities. Most of

Variation 53

these characters have to do with degree of inflation of the bullae.
Indirectly correlated with degree of inflation is first the extent of
remo\'al of the anterior margin of the bulla from the glenoid fossa
and foramen ovale, and second the form (convex, flat, or concave)
of the part of the squamosal bone between the foramen ovale and
the anterior margin of the tympanic bulla. As one proceeds south-
ward from, say, southwestern Kansas through the geographic
range of the species Mustela frenata, there is a progressive de-
flation of the bulla, an increase in length of the space between its
anterior margin and the foramen ovale, and the floor of the brain-
case in front of the bulla changes from ventrally concave to ven-
trally convex. (See figs, e and h of pi. 24 and figs, e and / of
pi. 27.)

One extreme of this variation in bulla is shown in Mustela frenata
neomexicana (fig. e of pi. 24), in which the anterior margin of the
bulla (viewed from the ventral side) rises vertically from the floor
of the braincase to form a 90-degree angle. The other extreme, the
uninflated bulla, is in Mustela frenata panamensis (fig. e of pi. 27),
in which the anterior margin of the bulla is not raised above the
floor of the braincase. This variation is remarkable because it oc-
curs within a single species. Otherwise, in the family Mustelidae,
differences in the tympanic bullae as great as that between the two
subspecies M. /. neomexicana and M. /. panamensis, occur only
between genera. The need for caution in inferring the limits of
variation for a particular structure in one species or genus, on the
basis of variation in another group, is therefore obvious.

Speaking now of full species, the most inflated tympanic bullae in
American weasels are in Mustela frenata, and more restrictedly in
those subspecies of it which occur in the temperate region. Sub-
species of M. frenata in Central and South America, as already
noted, have less inflated bullae. The tropical weasel, Mustela
africana, of the Amazon drainage of South America has the bullae
still less inflated (see fig. i of pi. 39 and fig. / of pi. 40). The bullae
are less inflated even than in the mink, subgenus Lutreola. In M.
africana the cleidomastoideus, omotrachelian, levator scapulae, and
rhomboideus profundus muscles take origin from a fossa on the
mastoid bone, whereas in the forms with greatly inflated bullae
these muscles take origin from a raised ridge or tubercle. Using
Mustela frenata of the temperate region as a starting point and pro-
ceeding northward, a reduction in inflation of the tympanic buUa
is seen also in that direction in that Mustela erminea has less inflated

54 University of Kansas Publs., Mus. Nat. Hist.

bullae. The bullae are less inflated in southern than in far northern
( arctic ) populations of Mustela erminea. In erminea the lesser in-
flation is real enough but at the same time there appears to be less
inflation than actually exists, for the squamosal floor of the brain-
case is "pushed down." This places the anterior end of the tym-
panic bulla farther in the bramcase than it otherwise would be.
Although the anterior end of the bulla is flattened to the extent
that it resembles the sharp edge of a splitting-wedge, inspection
of the lateral and medial edges shows that in its central part the
bulla is more inflated than it is in the weasels of Central and South
America.

For reasons set forth later, M. erminea is judged to resemble the
ancestral stem form more closely than does any one of the other
three American species of weasels. If this judgment is correct,
the shape of the tympanic bullae of the American weasels may be
explained as follows: In the subspecies of Mustela frenata of the
temperate regions of North America the bullae have most nearly
been pushed out of the braincase and at the same time have under-
gone some enlargement. The subspecies of this same species in
Central and South America represent an earlier stage in the evolu-
tion of American weasels and retain less inflated bullae — less in-
flated even than those of the southern subspecies of erminea. M.
africana probably separated from the stem form at a still earlier
time if we may judge by the lesser inflation of its tympanic bullae.
There are other reasons for tliinking that africana separated from
the stem form earlier than M. frenata did. During the time that
elapsed since the separation of M. frenata from the stem form, the
tympanic bullae of M. erminea probably increased slightly in size,
as probably also did the brain but without shoving the auditory
complex forward from its former position.

DISTRIBUTION AND SPECIATION

Weasels of the subgenus Mustela are known from the Pleistocene
but not from deposits laid down at an earlier time (see page 10).
The Pleistocene weasels from Rancho La Brea of southern Cali-
fornia and from Potter Creek Cave and Samwel Cave, both of
northern California, are subspecifically indistinguishable from the
weasels living in those same localities today. The other notable
occurrence of weasels in the Pleistocene is in the Conard Fissure
of Arkansas. Brown (1908:181, 182, pi. 17) names two kinds from
the Fissure. One is an extinct subspecies (Mustela frenata gracilis)
possibly of the species which occurs in the same region today and

Distribution and Speciation 55

the other, Mustela erminea? angtistidens, is an extinct subspecies
of a species which occurs only farther north today. M. erminea
came south, probably in front of one of the ice sheets, as did several
other species of American mammals, now of more northern distribu-
tion, tliat left their remains in Conard Fissure. Mustela rixosa is
not recorded as a fossil in America although it is known from the
"Diluvial" deposits of the Old World; see Woldrich (1884:1000),
who employs the name "Foetoriiis minutus n. sp.," and see also Zim-
merman (1943:295-296).

The ermine, Mustela erminea, is the most generalized of the full
species. For example, the number of teeth is as large as in any
other species and greater than in certain species. The teeth are
sharp-pointed, uncrowded, and individually less specialized than
in any other American weasel. Ml has the inner half, or lobe, of
approximately the same size as the outer lobe instead of much
larger than the outer lobe (the outer lobe is the larger in several
other species). The tympanic bullae are less inflated and less pro-
truded from the braincase. The skull is rounded, and has no
marked crests and ridges whereas the skulls of the other species
are more pronouncedly modeled and sculptured. Therefore, it is
possible to think of these other species as derived from M. erminea.
A derivation in the reverse direction would be more difiicult. From
the foot soles of an ermine, or a weasel closely resembling an ermine,
the more complex soles of Mustela africana could have been de-
rived by a decrease in hairiness, although it would be necessary to
suppose that the thenar pad has been retained in africana and has
been lost in the living erminea. The alternate possibility, namely,
that the thenar pad was a relatively recent acquisition in the africana
line seems less probable. The tail of erminea is of "average" length
and in size of entire animal erminea is intermediate between the
other American weasels. Structurally, Mustela erminea appears to
be nearest the stem form from which all of the living weasels as-
cended. Its present holarctic distribution is in harmony widi the
view that it is a direct descendant from the stem form because
the stem forms of most of the known kinds of mustelids appear to
have lived in the holarctic region. To be sure, Mustela erminea is
regarded as having undergone some progressive change in struc-
ture, but less than the other weasels, in the period of time when
the weasels were evolving from the stem form.

The least weasel, Mustela rixosa, seems to be an ancient type
and to judge from the size and proportions of its parts, was differ-
entiated from the erminea stem at a time earlier than were the other

56 University ok Kansas Publs., Mus. Nat. Hist.

American Recent species of weasels. In size, in reduction of tlie
tail, and in proportions of the skull, M. rixosa is, in each instance,
the most aberrant of all the weasels, Mustela nivalis of Europe and
western Asia included. This aberrancy results from the retention
of certain primitive features, in the teeth and basicranial region,
and from specialization in proportions of the skull. The skull is
long, deep, and narrow. These proportions probably are adapta-
tions permitting the animal to follow the smaller kinds of mice into
their burrows. In most of that part of North America where
erminea and rixosa occur togetlier, crminea is a much larger animal
and takes as prey almost all kinds of land vertebrates that it is
powerful enough to kill. These include varying hares and ptar-
migans. The least weasel, rixosa, can hardly manage such large
prey and Hves on the smaller rodents. Mustela rixosa may eat
numbers of insects (see page 176 beyond), — a kind of food which
Mustela erminea is not known to eat. Apparently the two species
are able to live in the same areas because each eats a somewhat
different kind of food than does the other and hence they do not
compete to the point where one is crowded out by the other. This
is the case in the latitudes where the two species of weasels are of
different bodily size, but in the southernmost latitudes where these
two species occur, erminea becomes almost as small as rixosa and
only one of the species, to the exclusion of the otiier, occurs in a
given area. All through the Rocky Mountains, south of Montana
and in the territory west of these mountains all the way to the
Pacific Coast, only the small subspecies of erminea is to be found.
In tlie Alleghenies of the eastern United States only rixosa occurs.
In New England where erminea approaches the size of rixosa, the
latter is unknown. Probably this exclusiveness results from compe-
tition for food, although competition for dens, safe breeding places
and other requirements of hfe may be involved.

The species erminea invaded the western United States and in
the process of invasion probably developed there the small size
appropriate to permit erminea to live in that latitude before it
could do the same thing in the Appalachian region. Later than
erminea, the least weasel, Mustela rixosa, which was small to begin
with, also spread southward from the holarctic region, stopped
short in the western United States at the northern boundary of the
area in which erminea was of small size, but in the Appalachian
region of the eastern United States continued on southward to the
limits of temperature tolerant for it because erminea had not yet
penetrated into that region and no other small carnivore was there
to offer competition.

Distribution and Speciation 57

The long-tailed weasel, Mustela frenata, occurs mostly south of
the regions inhabited by the ermine, and mostly south of the region
inhabited by the least weasel which appears to live as well with
frenata as with enninea. It is true that erminea and frenata occur
in the same region, but tliis is a relatively narrow belt across the
United States; and from within it a person cannot go far either north
or south without reaching a region in which only one of the two
species occurs. Exception has to be made for the Rocky Mountains
and the Sierra Nevada, where erminea is of exceptionally small size.
In these mountains and in the boreal mountainous parts of the inter-
vening region of the United States, erminea and the large-sized
frenata occur together over a wide area. Presumably the two oc-
cupy different ecologic niches, much as rixosa and frenata probably
do where they occur together.

Most of the geographic range of the long-tailed weasel, M . fre-
nata, is in the temperate region. Structurally, this species is the
most advanced of the American weasels. Its dentition is the most
highly specialized for cutting. Ml is relatively small and the inner
lobe is slightly larger than the outer lobe. The skull, throughout,
is more modeled than in the other species; the rostrum, the lower
jaws and the teeth — all parts of the offensive equipment — are well
developed relative to the corresponding structures in other weasels;
the basicranial region exhibits an advanced stage of development
in that the tympanic bullae show the maximum degree of inflation.
Also, they are thrust far out of the braincase, thereby providing
more room for the relatively larger brain which is protected by a
more solidly built braincase than in erminea.

Several subspecies of Mustela frenata occur in the tropics, that
is to say, south of the Mexican tableland and on the coastal plain
to the east of it. Each is structurally more primitive than subspecies
of the temperate region. As compared with Mustela frenata frenata
of the temperate Mexican tableland the size in these tropical sub-
species is smaller; the tail is shorter; the braincase and entire skull
are less modeled; the postorbital breadth is more; the teeth are
smaller; the deuterocone of P4 is not so far anterior to the protocone;
the tympanic bullae are less inflated, are farther removed from the
foramen ovale, and a larger proportion of each bulla is contained
within the braincase. These features serve to set off from northern
races of frenata all those subspecies of frenata which occur from
southern Mexico southward to the northern and western limits of
the Amazon drainage of South America. The Amazon Basin is in-
habited by another species, Mustela africana, having more primi-
tive characters.

58 University of Kansas Publs., Mus, Nat. Hist.

In the species frenata, the explanation for this abrupt change in
characters between the animals of the temperate highlands and
those of the tropical lowlands may be tiiis : In the early Pleistocene,
after the emergence of much or all of Central America took place,
weasels distributed themselves over the Isthmus and into South
America. These weasels were more generalized in structure than
those now inhabiting the uplands of Mexico. Failure of this stock
of weasels often to cross some still-persisting water barrier, or failure
of this stock to cross some water barrier that was widened or re-
formed because of a rise in sea level in some one of the interglacial
periods of the Pleistocene cut the frenata stock into two or more
parts. After the land connection was established or re-established
and when the necessary precedent plants and rodents again had
established themselves, the two groups of weasels, one from the
northern tableland of Mexico, and the other from the southern area
of tropical complexion, met. The weasels of the frenata stock that
reinvaded the area from the north probably did so by following
along the chain of high volcanic cones and narrow uplifts. If and
when a subsequent inundation occurred in some part of Central
America, weasels were stranded on the adjacent mountains —
converted into islands — only the higher parts of which were above
water. Mustela frenata costaricensis and MusteJa frenata goldmani
may be examples of a northern stock of weasel that pushed south-
ward in the highlands and became stranded for a short time. Fol-
lowing the latest emergence of land to provide a continuous high-
way between the two continents, weasels from the south and the
insular populations, as for example, M. /. costaricensis, were the
first to invade the low tropical areas most recently under water.
When the Pleistocene history of Central America is better known,
the facts will provide a useful means of testing the hypothesis that
has been outlined immediately above.

As explained above, fossil specimens of M. frenata from de-
posits of the last half of Pleistocene time show that no appreciable
change occurred in some areas, for example, in the vicinity of
Hawver Cave and Samwel Cave of California, and that but slight
change occurred in other areas, for example, in southern Cali-
fornia (fossils from Rancho La Brea) and probably in the central
United States (fossil from Conard Fissure). It is possible to
imagine, therefore, that the two groups of weasels, one occurring
southward only as far as the highlands of Central America and
the other occurring in northern South America, had not diflFerenti-
ated sufficiently in the period of their isolation to prevent cross-

Distribution and Speciation 59

breeding when they last came into contact. If the separation of
the two groups had been maintained for a longer period, the two
groups, tropical weasels and austral weasels, probably would have
been so different when the two met as to prevent crossbreeding
and they would have constituted two full species instead of only
one.

Mustela africana is the most primitive of the American weasels.
Some of the most important structural features that mark it as
such are in the basicranial region. The tympanic bullae are less
inflated than in other weasels, are pointed anteriorly and posteri-
orly, and do not have the lateral margins carried outward to the
outer margins of the braincase. The mastoid sinus is not involved,
by inflation or marked modification in the production of the audi-
tory complex. Between the alisphenoid and the squamosal there
is a clear demarcation posteriorly from a point directly lateral
to the foramen ovale. This demarcation permits a transverse
rounding of the ahsphenoid to form a longitudinal ridge between
the anterior margin of each bulla and the base of the pterygoid
of the same side. Nevertheless, there is no such specialization
of this primitive, structural feature such as occurs in some African
and Asiatic mustelids in which the tympano-pterygoid part of
the ahsphenoid fuses with the tip of the hamulus of the pterygoid.
However, the tympano-pterygoid eminence has not been obliter-
ated in M. africana as it has in the other American weasels. An-
other primitive feature in the basicranial region of M. africana is
the tendency toward separation of the paroccipital processes from
the tympanic bullae. The thenar pad of the foot probably is an
inheritance from a primitive ancestor since the pad is present in
the viverrids and in a majority of mustehds judged to be more
primitive than Mustela.

Some specializations are obvious in Mustela africana. One is the
reduction in number of premolars; p2 is absent whereas it is nor-
mally present in the other weasels; P2 has one instead of two roots;
and, in relation to the other teeth, m2 is smaller. The shortness of
the preorbital part of the skull in relation to the length of the
skull as a whole may reflect the mentioned reduction of the pre-
molars or retention of a primitive shape of skull, or both. Also, cer-
tain features which denote immaturity in other weasels are re-
tained in adults of this species, as for example, sutures on the dor-
sal face of the preorbital region of the skull.

Mustela africana, all characters considered, is the most aberrant

60

University of Kansas Publs., Mus. Nat. Hist.

17

Wm

mi

18

20

%:'P

If.vr

:^.

Figs. 17-22. Views of the feet of American weasels (subgenus Mustela) to
show differences in number and arrangement of the pads and variation in de-
gree of hairiness of the soles. X 1/2- In each figure, left-forefoot on left, and
left hind foot on right.

Fig. 17. Af. rixosa rixosa, HaUfax, N.S.; juv., 9, 7425 U.S.N.M.

Fig. 18. M. erminea richardsonii. Ft. Chimo; ad. $ , 14866 U.S.N.M.

Fig. 19. M. frenata noveboracensis, Mich., July 7, 1913; ad. $ , 44689 M.Z.

Fig. 20. M. /. frenata, Brownsville, June 1, 1892; yg. $ , 34043 U.S.N.M.

Fig. 21. M. frenata panamensis, Panama, February 17, 1911; sad. 9, type.

Fig. 22. M. a. africana. Para, Brazil, Sept., 1908; yg. $ , 37475 A.M.N.H.

Figs. 17, 18 and 19. Drawn from specimens preserved in alcohol.

Figs. 20, 21 and 22. Drawn from relaxed feet of dried skins.

Distribution and Speciation

61

of the American weasels. That is to say, greater difference pre-
vails between M. africana and any other American weasel than
exists between any other two American weasels. The distinctive
cranial and dental characters, excepting the reduction in number
of premolars, are of a primitive nature. For example, the relatively
wide postorbital region, the large braincase that is inflated an-
teriorly, and the flattened tympanic bullae are points of resemblance
to the holarctic Mustela erminea, the species which is regarded as
most closely resembling the stem form. Also, the mentioned char-
acters in adults of M. africana resemble ontogenic stages passed
through by other weasels. Consequently, it is thought that M.
africana crossed the filter-barrier from North America to South
America, remained isolated from the original stock for a length of
time sufficient to permit africana to differentiate from North Ameri-
can weasels and vice versa to such a degree that crossbreeding with
the frenata stock was prevented when frenata, at a later time, pushed
southward over the, then zoologically less-effective, water-barrier,
or continental bridge if it was by this time in existence.

The four full species of American weasels may well be thought
of as having the same stem form of which erminea is the most nearly
direct descendant. Geographic and climatic changes may have
operated to isolate, and then to foster morphologic differentiation

Fig. 23. Diagram indicating probable relationships of the species of

American weasels.

62 University of Kansas Publs., Mus. Nat. Hist.

of, first rixosa in Eurasia, next africana, third the tropicalis section
of M. frenata, and finally M. frenata itself, leaving M. erminea as
a modem version, somewhat altered to be sure, of the stem form.
Some of these ideas are expressed in figure 16. The climate is dif-
ferent in the ranges of the several species and the chmate has
changed through time in the ranges of at least many subspecies.
Natural selection of morphological features best adapted to a par-
ticular kind of climate probably has altered some species more
than others. M. erminea in almost every one of its characteristics
is generalized and potentially progressive whereas africana retains
more characters which are truly primitive along with a few which
are specializations. M. africana is potentially the least progressive
of any of the American weasels. The most specialized weasels are
the North American races of Miistela frenata. A progressive series
of increasing specialization is comprised in (1) M. africana, (2) the
M. tropicalis (Central American, lowland) section of M. frenata,
and (3) the races of M. frenata in North America.

Considering now features of the environment which have ob-
viously influenced the distribution and speciation of weasels, water
barriers are important. Bering Strait, Carquinez Strait ( along with
San Francisco Bay) which opens through the Golden Gate, and the
channels between the islands of southeastern Alaska, have con-
tributed to the formation of subspecies. The di£Ference is really
shght on the two sides of Bering Strait and San Francisco Bay and
is slightly more on two sides of each of several of the channels be-
tween the islands of southeastern Alaska. The differences between
the weasels on the two sides of one of these water barriers sup-
posedly result from the preservation in animals on one side, or on
one island, of small mutations, which would be swamped by cross-
breeding if the water barrier were not present. The effect of this
isolation is easily seen if ermines from the Queen Charlotte Islands
are compared with those of the opposite mainland. The degree of
morphological difference is great. Isolationwise, the Queen Char-
lotte Islands are the seaward end of a chain, beginning with Ad-
miralty Island in southeastern Alaska, and are farther from the main-
land, zoologically, than the distance in actual miles across the water
channel would suggest. Between any two islands that are geo-
graphically consecutive, however, and between the mainland and
the first island of the chain, the difference in tlie ermines is small.
In other places, water barriers of equal or greater width have con-
tributed little if anything to the differentiation from one another

Distribution and Speciation 63

of weasels on the two sides of the water barrier. The strait between
eastern Canada and Newfoundland is an example.

The absence of water, or scarcity of it to a degree that closely
approaches absence, in any large area appears to prevent weasels
from living there. At any rate, the one sizeable region of North
America from which weasels are unknown is the desert of the south-
western United States and adjoining part of northwestern Mexico.
More precisely, in western Arizona, the Mohave Desert and the
desert of northwestern Sonora, collectors of mammals have repeat-
edly sought small carnivores without ever finding any weasels.

Degree of moisture is closely correlated with color in weasels.
Humidity and cloudiness as well as actual precipitation seem to be
involved. Even if we take into account average annual rainfall
alone, the darkest-colored weasels are found in the areas of heaviest
rainfall and the lightest-colored weasels in areas of lightest rainfall
(extreme type of desert where no weasels occur being excepted).
In any large region where there is a geographic gradient in rainfall,
the transition from light to dark color almost exactly parallels the
increase in amount of rainfall. Within a given species the same
color reappears in wiidely separated areas that have the same
amount and seasonal distribution of rainfall. This correlation is re-
peated so 6ften that one can almost certainly say that heavy rainfall,
or the associated phenomena of high humidity and cloudiness, act-
ing separately or together, causes an increase in intensity of color.
Relative extent of the color of the upper parts and underparts and
presence and absence of light facial markings seem also to be cor-
related, in a more general way, with differences in rainfall. A fuller
discussion of the nature and amount of the variation in color is
given on page 51.

Temperature seems not to be an important factor in directly lim-
iting the distribution of weasels, since M. frenata occurs from the
hottest to some of the coldest parts of the Americas. Do M. erminea
and M. rixosa range no farther south, than they do at present, be-
cause high temperatures constitute a barrier? No evidence is
known to me which provides an answer, one way or the other, to
this question. Granting that temperature is unimportant in limiting
the distribution of weasels, it seems to cause geographic variation.
Increase in mean annual temperature is correlated with decreased
size in M . erminea and with increased size in M. rixosa. Temper-
ature, it seems, causes the hair to vary; the pelage is harsher and
sparser in weasels from tropical regions than in those from boreal
regions. Difference in number of hairs is especially well shown on

64 University of Kansas Publs., Mus. Nat. Hist.

the soles of the feet. In the weasels from the far north, the pads are
concealed by hair and in the weasels from the tropical regions tlie
soles are mostly bare. Also, the hair on the soles of the feet is
longer in northern than in southern weasels. Furthermore there is
seasonal change in length of the hair on the soles of the feet; at a
given locality in southern Canada tlie hair of the white winter coat
is so long on the soles of the feet as to obscure completely the
palmar and plantar pads whereas the hair of the brown summer
coat is shorter and leaves these pads boldly exposed to view. This
seasonal change, as would be expected, is most marked in animals
of northern regions and is not perceptible in those from the tropics;
it is correlated with increase in seasonal change as the distance from
the equator increases.

Temperature and moisture acting together may cause extensive
white facial markings, that neither alone would cause. In Mtistela
frenata these markings occur where there is heavy rainfall and high
mean annual temperature. Where tliere is heavy rainfall and a
low mean annual temperature they do not occur and where there
is high mean annual temperature and light rainfall the markings are
not pure white but are of the same color as the underparts. Plate
I and the description of color on page 51 may be consulted in this
connection. Extremely high mean annual temperature together witli
extremely heavy rainfall may inhibit the development of light facial
markings. M. f. meridana, panamensis and costaricensis are cases
in point. In either direction, north or south, from the territory
inhabited by tliese three subspecies a similar combination of tem-
perature and rainfall is found and similar light facial markings ap-
pear there.

Considering the delicate response of structure to cHmate, a
person naturally questions whether or not natural selection ac-
counts for all of the differences between subspecies. To show that
natural selection determines the color of Mustela frenata, it would
be necessary to assume that climate, color, and utihty of color are
positively correlated. Although climate (rainfall) and color are
correlated in such a manner that three subspecies of weasel in
places as far apart as New England, Peru, and the state of Wash-
ington are colored alike, other features of the three environments
are unhke. Kinds of animals which the weasel catches for food,
and flora in which the weasel finds concealment, are dissimihar.
If natural selection alone determined the color, some difference
in color would be expected between the weasel which needed
to be obliteratively colored, that is camouflaged, the better to catch

J

Distribution and Speciation 65

a Phyllotis in Peru and the weasel in Washington which needed
nature's aid in catching Microtus. Miistela frenata goldmani of
the highlands of southern Mexico, which is known to attack the
huge pocket gophers, Orthogeomys and Cratogeomys, has a weaker
dental armature than Mustela frenata texensis which does not have
to overcome prey so formidable as does goldmani. Equally formi-
dable enemies endanger M. f. goldmani and texensis. Examples of
this nature could be multiplied. Without actually proving anything
concerning selection, these examples give reason for us to suppose
that some characters are not determined by natural selection.

Another question upon which data obtained from a study of
Mustela has some bearing, is this: Where the geographic ranges
of two subspecies meet, why does not the swamping effect of
crossbreeding cause one subspecies to disappear? Although
swamping may have occurred in some instances, it does not occur
in the majority of instances. Witness the long-continued existence
of the living subspecies Mustela frenata nevadensis of which skulls
are available from Pleistocene deposits. Therefore, its distinctive
characters, cranially at least, have been maintained for a long
time. Furthermore, these characters are maintained over a large
geographic region more than a thousand miles across. On the
eastern margin of its range, at the eastern base of the Rocky Moun-
tains in Colorado, M. f. nevadensis intergrades in a relatively
narrow belt with the lighter-colored, longer-tailed and cranially
different Mustela frenata longicauda, which has a geographic range
almost equally extensive. M. f. longicauda also is uniform in its
characters over a large area but at approximately 400 miles east
of the base of the Rocky Mountains, it begins to intergrade with
the darker-colored, shorter-tailed and cranially different Mustela
frenata primtdina and does so over a belt of 100 miles or more in
width. At any given locality within this wide belt of intergrada-
tion the range of individual variation ordinarily does not exceed
that in animals from a given locality well within the geographic
range of M. f. longicauda. In the narrow belt of intergradation
along the eastern base of the Rocky Mountians, the range of indi-
vidual variation at several places is greater than in animals from
a given locality well within the geographic range of M. f. longi-
cauda or for that matter from well within the geographic range of
M. /. nevadensis.

Considering the dominance and recessiveness of genes and the
genetic mechanism in general by which characteristics of offspring

3—3758

66 University of Kansas Publs., Mus. Nat. Hist.

are inherited from their parents, it would seem that M. f. longi-
cauda and for tliat matter M. f. nevadensis and M. f. primulina
would lose their distinctive characteristics because of the cross-
breeding that is every year going on between longicauda and
nevadensis on the one hand and between longicauda and primu-
lina on the other hand.

Sumner (1932:84) suggests that homogeneity is prevented by
population pressure. Applying his suggestion to the species Mus-
tela frenata we could say that the subspecies longicauda pressing
westward meets strong pressure from the subspecies nevadensis
pressing eastward and that the width of the zone of intergrada-
tion between the two subspecies varies inversely with the strength
of the population pressure from the two sides. Sumner recognizes
that according to his hypothesis the two contiguous races would
remain distinct only so long as there was a preponderance of centri-
fugal movement from both of the centers of dispersal. Sumner
{op. cit. :85) recognizes that an abrupt change of environmental
conditions could account in part for the boundaries of the ranges
of the two subspecies and finally that his hypothesis does not cer-
tainly answer the question of why crossbreeding does not result
in homogeneity between two subspecies with contiguous geo-
graphic ranges.

The hypothesis of harmoniously stabilized complexes of genes
was offered by Timofeeff-Ressovsky (1940:124) to explain why the
swamping effect of crossbreeding does not obliterate subspecies.
The hypothesis takes into account that any one of several char-
acters of a subspecies may be caused by several genes. Some char-
acters of this kind may be favored by natural selection more than
others. In the belt of intergradation between two subspecies, where
two of these favored characters meet, a 'Tjiological tension" as Hux-
ley (1939:415) terms it "will result, which will produce partial dis-
continuitij between the two groups. Each group will evolve a
gene-complex which is not only broadly adapted to the external
environment of the central area of its range, but is also harmo-
niously stabilized, in adaptation to the internal genetic environment,
by the selection of modifiers." Crosses, that is to say intergrades,
between the two subspecies will lack this stabilization and will
therefore be at a selective disadvantage. The zone of intergrada-
tion will therefore remain narrow; intermediates are constantly
being brought into existence there by crossing but are as constantly
being extinguished by selection.

These two hypotheses are the best that geneticists yet have of-

Distribution and Speciation 67

fered. Neither has been tested and both, as originally proposed,
would hardly apply everywhere because there are some contradic-
tions.

I can offer no better explanation — in fact no original one as good
— but would emphasize that under similar climate, weasels remain
constant in character, or at most do not vary beyond certain hmits.
Crossing at the margins of ranges of two subspecies does not re-
sult in homogeneity of weasels. There is, therefore, some sta-
bilizing influence, or influences, that maintain, and even develop,
structural characteristics of weasels in opposition to the contrary
tendency of crossing.

That this influence not only maintains uniform characters over
areas of large extent, but also permitted their development over
large geographic areas, must logically be supposed, for otherwise,
considering the swamping effect of crossing, such variations would
not have made their appearance in more than a few individuals.
Also, if the races had been formed in response to some kind of
physiological differentiation, or other non-chmatic cause, the char-
acters of the population in the belt of intergradation probably would
disappear in a short time. In any event the close correlation be-
tween degree of change in weasels and degree of change in climate,
at once makes one suspect that climate has been the deciding fac-
tor. Finally, when one recalls that in certain parts of the animal,
certain characters invariably appear under similar climates and
never under dissimilar climates, the evidence is almost conclusive
that, given long enough time, the animals vary in response to cli-
mate. The variations (characters) may be induced indirectly, but
are no less exactly reproduced than if they can be shown to be in-
duced directly.

In considering how the species and subspecies of American
weasels were formed and in attempting to account for some of the
individual characters, it is profitable to view the facts in the light
of some of the theories of species-formation — theories that are ac-
cessory to that of organic descent and that are concerned with the
modus operandi of organic descent.

In any group of closely related species some of them, by the laws
of chance, are almost certain to be more primitive than others.
Mustela is no exception and the more primitive species closely
match, in several characters, ontogenetic stages passed through by
more advanced species. Jaeckel's (1902) theory of metakinesis,
therefore, is to be considered since it postulates that many cases of
epistasis occur; that is to say, that many sexually adult animals are

68 University of Kansas Publs., Mus. Nat. Hist.

arrested in development in early otogenetic stages and undergo no
further development. Although this theory is appealing upon
initial consideration, it is less so when we recall that in Mustela
there is a direct correlation of increasingly primitive structure with
decreasing latitude as one proceeds from the steppe of North
America southward to the equator. It follows that the conditions
seen in Mustela can be explained even better than by metakinesis,
by assuming that the several species have differentiated from a
stem form at different times, have developed at different rates, have
developed in different directions and that ontogeny recapitulates
phylogeny.

The theory of Age and Area (see Wilhs, 1922) holds that the
species of widest distribution are, on the average, the oldest, and
that the species which are distributed over small areas are, in gen-
eral, of recent origin. So far as the weasels are concerned, httle
support is given to this theory. The same can be said of any one of
the teological theories, including the orthogenesis of post-Darwinian
writers. All of these imply a determinate line of variation controlled
by the inherent qualities of the organism. The idea that the several
species of Mustela result from mutations of large degree and sudden
appearance is contrary to the evidence accumulated. In fact the
evidence rather clearly indicates that the mutations which may
have occurred were of small degree and in most instances owe their
preservation to natural selection.

The data obtained by the study of weasels accords almost exactly
with the theory of species-forming embodied in Matthew's (1915)
"Climate and Evolution." Although the essential features of this
theory were made out from a study of families and orders and
therefore would not be expected to apply to members of only a
genus or subgenus, the facts known about the present distribution of
American Mustela, nevertheless, are strikingly in accord with the
ideas advanced by Matthew. In the first place, climate is an im-
portant factor in the evolution of the weasels. In the second place,
the line of migration seems to have been outward from the holarctic
region. In the third place, the geographic changes necessary to
explain the present distribution of the species of Mustela are not
extensive and do not affect the permanency of oceans as defined
by the continental shelf. These three statements are, almost ver-
batim, those made in the first three of the five points of Matthew's
(1915:172-173) thesis. The remaining two points of Matthew's
thesis have to do with generalizations based on evidence obtained
from sources outside the scope of the present study.

History of Classification 69

Furthermore, the relative degrees of speciahzation of the different
species and subspecies in relation to their geographic distribution
are in accord with the ideas elaborated by Matthew. For instance,
the most primitive species is farthest south from the probable
center of dispersal, the holarctic region. Also the full species be-
come progressively more primitive as one proceeds southward from
the holarctic, or at least from the northern half of the nearctic,
region. Although, in view of the known geological changes that
have occurred in the Caribbean region, we cannot say that the
more primitive species owe their positions entirely to having been
pushed farther south from the center of dispersal by actual and
continuous contact and competition with the more advanced species,
this seems to have been the case in a general way. At any rate
the more primitive kinds seem to have been prevented from push-
ing northward by the more advanced kinds which developed there
and the latter have actually pushed southward.

Additionally and in review: There is strong indication that the
American species of weasels were formed by gradual and slow
change. Much of this change probably is the result of natural
selection operating on fortuitous variations of a minor nature, but,
also, particular features of the environment, especially climate, and
more especially amount of rainfall, seem to compel variations that
differentiate subspecies and that characterize full species — compel
some of them without the direct operation of natural selection,
or at least compel them within limits so wide that natural selec-
tion exerts no exact control.

HISTORY OF CLASSIFICATION

In the earlier accounts of American weasels, from the time of
Linnaeus and before, up until 1890, names then in use for
European weasels frequently were applied also to those in North
America. For the next 50 years, and almost without exception
after 1896, the American weasels were regarded as specifically
distinct from those in the Old World. In this 50-year period
many new names were proposed, usually as full species, although
now that material from more localities has been brought together
and studied, geographic intergradation is evident between many
of the named kinds and most of these names now therefore take
only subspecific rank. In 1933 Glover M. Allen showed that
Mustela rixosa occurred also in the Old World, and in 1943 I
emphasized that a second American species, Mustela erminea, was

70 University of Kansas Publs., Mus. Nat. Hist.

circumpolar in distribution. In neither rixosa, nor erminea, how-
ever, w^ere the subspecies the same in the two continents. To this
general outhne of the nomenclature, exception must be made for
weasels of the southwestern United States, Mexico and Central
America, and South America, because as early as 1813 a distinctive
name was given to one of these and weasels from the three areas
mentioned were, so far as I know, never given names of Old
World kinds.

The first paper that could be regarded as revisionary in nature
was "Remarks on the species of the genus Mustela" by the
zoologist and world-traveler, Charles L. Bonaparte, in Charles-
worth's Magazine of Natural History, for 1838. In that paper
three new names, Mustela cicognanii, M. richardsonii and M.
longicauda, all still valid, were proposed for American weasels.

Audubon and Bachman in their "Quadrupeds of North America",
which appeared in parts from 1845 to 1853, recognized 5 species.
Actually they were dealing with only 3 taxonomically valid kinds.
For one of these, Mustela frenata noveboracensis, they were misled
by the difference in size between males and females, and in the
males by the presence of a broviTi coat in some and a white coat
in others. The male that was white in wdnter they regarded as
Putorius ermineus of the Old World; the male that was brown in
winter they designated by their earher proposed name P. fuscus,
and the female they named P. agilis. The ermine, subspecies M.
erminea cicognanii, they called P. pusillus. Their fifth name, P.
frenatus, included at least some animals that today are assigned to
the subspecies M. frenata frenata. Each of three and perhaps four
of the five names employed by Audubon and Bachman embraced
individuals of more than one species and in that sense the names
were composite.

Only five years later, in 1858, Professor Spencer Fullerton Baird's
great work, "The Mammals of North America", made it clear that
no American weasel was identical ( in the modem subspecific sense )
v^th any Old World weasel, and he applied most of his names in
a correct zoological sense. It is true that he thought that the fe-
male weasel of the eastern United States was specifically different
from the male, misapplied to it the name richardsonii, and did not
correctly allocate everyone of the few poor specimens available to
him of the little ermine ( M. e. streatori ) of the Pacific Coast; but
he did recognize that the least weasel was a distinct kind and his
treatment in general was excellent.

After Baird came a period of great confusion in which most

History of Classification 71

writers did no better than had Audubon and Bachman, ordinarily
confusing the two sexes as different species, and, in 1877 in his
"Fur-bearing Animals," Elliot Coues went rather to the other ex-
treme and allowed only 4 kinds to all of the Americas, regarding
two of these, for purposes of zoological nomenclature, as identical
with the European species.

But, in 1896 Outram Bangs published "A Review of the Weasels
of Eastern North America" in which he correctly recognized eight
kinds. Although some of these were treated by him as full species,
whereas the material accumulated since 1896 has shown that sub-
specific status is in order, his names, still in use, were correctly ap-
plied in every instance, save probably one. This was his use of
Putorius richardsonii for the animal now known as M. e. arctica.
Unlike the earlier, excellent treatment by Baird, this accurate one
by Bangs was heeded and followed by subsequent writers. For
example. Dr. C. Hart Merriam in the same year, 1896, accepted
Bangs' conclusions except for correcting the application of the name
richardsonii. The principal contributions of Merriam's paper "Syn-
opsis of the Weasels of North America" were first, the wider geo-
graphic scope and second, the naming as new of several kinds out-
side the geographic area studied by Bangs. Otherwise the work
was not up to Dr. Merriam's usual standard and the internal evi-
dence of haste in its preparation and the superficial study of some
of the material at his disposal explain why the weasels of North
America since that time have been but little better understood than
in 1896. Baird and Bangs, then, unquestionably did the best sys-
tematic work on the American weasels.

In 1916 Dr. Joseph A. Allen published a valuable paper on the
South American weasels. The material available to him was inade-
quate and prevented a thoroughly satisfactory treatment. There
are too few specimens even today to permit of a thorough treat-
ment of the South American weasels in the present paper; never-
theless the material today is more nearly adequate than it was
in 1916 and it is hoped that the systematic arrangement is corre-
spondingly improved.

Chronological List ( annotated ) of Specific and Subspecific
Names AppHed to American Weasels

At least eighty-seven specific and subspecific names have been
proposed for American weasels. Of these sixty-nine are now re-
garded as valid designations of recognizable subspecies. The aver-
age is 1.2 names per subspecies. Some names in the following
chronological list were a second time applied wholly or in part to

72 UxivERSiTi' OF Kansas Publs., Mus. Nat. Hist.

some other kind of weasel. In general, mention of the second or
any other later appHcation is omitted from the following hst but
two usages of agilis (1844 and 1853) and of americana (1865) are
recorded.

1734. javonica (Mustela) Seba, Locupletissimi Rerum naturalium Thesauri
. . ., 1:77, 78, pi. 48, fig. 4. The weasel to which this name was applied
was said to have come from Java. Since no animal answering to the description
has again been found in Java, and because specimens from Central America
or possibly some from northern India, may do so, it is conceivable that Seba
was the first to distinguish by name an American weasel from those in the Old
World. My attempts to locate the specimen concerned in places where it
might have been preserved along with some of the other specimens thought
to have belonged to Seba have been fruitless. Since it is impossible positively
to link Seba's description with any known weasel, no further use is made of the
name javonica in the present account.

1772. erminea (Mustela) Forster [= Mustela enninea richardsonii], Philos.
Trans., London, 1772:373. Forster's use of the name is one of the earliest
applications of it to American animals. The name dates from Linnaeus, Syst.
Naturae, (10th ed.) 1:46, 1758, with type locality in Europe. In the subspe-
cific sense the name applies to the ermine which occurs over most of the
Scandinavian Peninsula, if Miller ( 1912:387) be followed in regarding the type
locality as Upsala, Sweden. If, instead, Cabrera (1913A:394-396) be followed
in regarding the type locality as in Switzerland, the name, in the subspecific
sense, will apply to the ermine of continental Europe. As the earliest available
name applied to the circumpolar species concerned, it is used now as the name
of the species in the New World as well as in the Old World. From the time
of Forster imtil approximately 1890 tlie name erminea by many, but not by all,
authors was appUed to the American weasels in the beHef that they were
zoologically indistinguishable from those in the Old Worid. From 1896 to 1943
the name was not used by American authors at all because the ermine of
America was in 1896 treated nomenclaturally by Merriam as specifically dis-
tinct from the animal in the Old World. Since 1943 erminea has been used
in the specific sense for American animals in recognition of the circumpolar
distribution of the species. Some of the early allocations of American speci-
mens to erminea probably resulted in a composite use of the name in that one
or another subspecies of the American species Mustela frenata may also have
been included with individuals truly of tlie species erminea.

1772. nivalis (Mustela), Forster, Philos. Trans., London, 1772:373. This
is one of the early applications of this name to American weasels of small
size, made in the belief that they were taxonomically the same in America
and Europe. Linnaeus, Syst. Nat. (12th ed.) 1:69, 1766 is the authority
for the name [Mustela] nivalis, and the Province of Vesterbotten, Sweden,
is regarded as the type locality. The name is in use today for the common
weasel of Europe and parts of Asia. Animals of the species nivalis are inter-
mediate in size between Mustela erminea and Mustela rixosa. The name as
used for American animals by some authors who wrote later than Forster did,
probably was composite in that these authors may have applied the name to
the small weasels of North America and thus may have intended it to apply

History of Classification 73

not only to Mustela erminea cicognanii but also to females of Mustela frenata
noveboracensis, and conceivably to both sexes of Mustela rixosa of any
American subspecies.

1813. Brasiliensis (Mustela) SewastianoflF, Mem. Acad. Imp. Sci. St. Peters-
burg, 4:356-363, table (= plate) 4. This name was proposed for a weasel
brought to St. Petersburg by Capt. Krusenstem on his return from a voyage
around the world. The animal was said to have come from Brazil, but to
judge from the description, came instead from Mexico, Central America, or
west of the Andes in South America, and was based on some one of the
subspecies of Mustela frenata. Although the name was in use for more than
60 years it was shown by Merriam (1896:27) to be unavailable because it
was preoccupied by Mustela brasiliensis, a name earlier used by Gmelin (Syst.
Nat., ed. 13, p. 93, 1788) for a South American otter.

1815. vulgaris (Mustela), Ord, Guthrie's Geography as reprinted by Rhoads
in 1894, vol. 2, p. 291. This use by Ord is one of the earliest applications of
this name to American weasels, in the belief that the smaller weasels of North
America and Europe were zoologically the same; [Mustela] vulgaris seems
originally to have been proposed in 1777 by Erxleben on p. 471 of vol. 1 of
his Syst. Regni Anim., for the weasel of the temperate part of Europe and to
be a synonym of Mustela nivalis Linnaeus ( 1766 ) . Probably the name as
used by Ord was composite in the sense that he may have intended it to
apply to females of Mustela frenata noveboracensis as well as to one or both
sexes of Mustela erminea cicognanii and, if he ever saw them, to the two
sexes of Mustela rixosa ( one or several subspecies ) .

1818. africana (Mustela) Desmarest [^Mustela africana africana], Nouv.
Diction, d. Hist. Nat., 19:376. In 1808 E. GeoflFroy St.-Hilaire visited Portugal
and was given several African primates and the specimen of Mustela named
by Desmarest in 1818 who wrongly supposed that it, like most of the primates,
came originally from Africa. After the name had been misapplied for 95
years Angel Cabrera showed that it pertained instead to the tropical weasel
of Brazil. Of distinctive names applied to American weasels today, this is
the one first proposed.

1832. frenata (Mustela) Lichtenstein [^= Mustela frenata frenata], Darstel-
limg neuer oder wenig bekannter Siiugethiere, pi. 42 and corresponding text
unpaged. This name is the first one available for the long-tailed weasel and
therefore applies to the species as a whole.

1838. Cicognanii (Mustela) Bonaparte [=i Mustela erminea cicognanii],
Charlesworth's Mag. Nat. Hist., 2:38. The name erroneously spelled Cigog-
nanii was correctly spelled on page 39. For a detailed consideration of this
name see the account of the subspecies cicognanii on page 120.

1838. Richardsonii (Mustela) Bonaparte [=: Mustela erminea richardsonii],
Charlesworth's Mag. Nat. Hist., 2:39. Until 1896 the name sometimes was
applied to the subspecies now known as M. e. arctica and sometimes to part
of the subspecies now designated as M. e. cicognanii under the principal treat-
ment of which see (page 120) for a detailed account of the basis of the name
richardsonii, and the reasons for regarding Fort Franklin as the type locality.

1838. longicauda (Mustela) Bonaparte [= Mustela frenata longicauda],
Charlesworth's Mag. Nat. Hist., 2:39. The type locality appears to be Carl-

74 University of Kansas Publs., Mus. Nat. Hist.

ton House, Saskatchewan, and the name always seems to have been appUed to
the long-tailed weasel of the Great Plains, although in some earher accoimts
the name was used in a more inclusive sense to refer also to animals now of
subspecies closely alUed to longicauda. As with the two preceding names, a
detailed consideration of the basis for, and application of, this name is given
on pages 120-123 in the account of Mustela erminea cicognanii.

1840. Noveboracensis (Putoritis) Emmons [^Mustela frenata novebora-
censis]. Quadrupeds of Mass., p. 45. This name was credited by Emmons to
De Kay who in the same year published it in his report on the "Zoology of
New York" but without a description and De Kay's name is a nomen nudum.
Emmon's was the first use of the name accompanied by a recognizable de-
scription and therefore the name must date from Emmons although this ob-
viously was not his intent since he credited the name to De Kay.

1842. fuscus (Putorius) Audubon and Bachman [^Mustela frenata nove-
boracensis]. Jour. Acad. Nat. Sci., Philadelphia, 8: (pt. 2) 288.

1842. pusilla (Mustela) De Kay [z= Mustela erminea cicognanii], Nat. Hist,
of New York, Zool., Pt. 1, Mammalia, p. 34. This name was proposed for
small weasels of 12 to 13 inches in length of which the tail amounted to a
fourth of the same and although obviously applying in considerable part to
the earher named M . e. cicognanii seems to have included some individuals of
the also earlier named M . /. noveboracensis.

1843. xanthogenys (Mustela) Gray [^Mustela frenata xanthogenys], Ann.
and Mag. Nat. Hist., 11:118, February, 1843, was applied to all of the long-
tailed weasels of California that had hght-colored facial markings. Merriam
in 1896 suggested that San Diego was the type locahty and in 1899 Bangs
proposed the name mundus for the California weasel north of San Francisco
Bay thus restricting the application of the name xanthogenys. In 1936 Hall
further restricted the apphcation of the name and applied it to the long-
tailed weasel of the big interior valley of CaUfomia, pointing out that the
name was correctly applied to this weasel of the big interior valley or possibly
instead to the race named munda.

1844. agilis (Mustela) Tschudi [= Mustela frenata agilis], Untersuch. ii. die
Fauna Peruana, p. 110, is a name apphed today to the race of weasel of the
Temperate Zone of the western Andes and intermountain valleys of Peru.

1851. nigripes (Putorius) Audubon and Bachman [= Mustela nigripes],
Quadr. N. Amer., 2:297, 1851, applies to the black-footed ferret of North
America.

1853. agilis (Putorius) Audubon and Bachman [= Mustela frenata nove-
boracensis], Viv. Quadrupeds N. Amer., 3:184, pi. 140. This name was pro-
posed for the female in the mistaken belief that it was specifically distinct from
the larger male for which several names already were available. Also Tschudi
in 1844 had already used the name Mustela agilis for a South American weasel.

1864. aureoventris (Mustela) Gray [= Mustela frenata aureoventris], Proc.
Zool. Soc. London, 1864:55, pi. 8, February 9, 1864, is the name applicable to
the dark-colored weasel of the Pacific coastal region of Ecuador and Columbia.

1865. americana (Mustela erminea Var. 3) Gray, Proc. Zool. Soc. London,
1865:111. The larger individuals of American weasels of both Mustela erminea
and Mustela frenata from the Atlantic Coast to as far west as Carlton House,

History of Classification 75

Saskatchewan, were lumped under this name because Gray desired more in-
formation than he then had before recognizing as diflFerent from one another
several species proposed for America up to the time concerned. The name is un-
available because it is preoccupied by Mustela americana Turton (1806) the
name for the American marten.

1865. americana {Mustela vulgaris Var. ) Gray, Proc. Zool. Soc. London,
1865:113. Under this name the smaller weasels of the northern and north-
eastern part of North America were lumped by Gray but the name is pre-
occupied and can be ignored.

1874. afiinis (Mustela) Gray [=: Mustela frenata affinis], Ann. and Mag.
Nat. Hist., 14 (ser. 4):375, 1874, from New Granada [= Colombia], had the
type locality restricted to Bogota, Colombia, by Allen in 1916, and is applied
to the long-tailed weasel of the tropical and temperate zones of the eastern
Andes of Colombia.

1874. macrura (Mustela) Taczanowski [^Mustela frenata tnacrura], Proc.
Zool. Soc. London, for 1874, p. 311, pi. 48, May 19, 1874, applies to the long-
tailed weasel of central Peru and northern Ecuador.

1877. culbertsoni (Futorius) Coues [= Mustela frenata longicauda]. Fur-
bearing animals . . ., p. 136, 1877, is based on specimens from Fort Lara-
mie, Wyoming. In the past the name has been regarded as a nomen nudum
but there is some reason for regarding it as having nomenclatural status. In
either event it is here arranged as pertaining to the long-tailed weasel of the
Great Plains which takes the prior name longicauda. See the account of longi-
cauda for a more detailed account of the name culbertsoni.

1877. aequatorialis (Putorius (Gale) brasiliensis) Coues [= Mustela frenata
aureoventris], Fur-bearing animals . . ., p. 142. Proposed "merely as a
substitute for Gray's [supposedly] preoccupied name," aureoventris.

1881. stolzmanni (Mustela) Taczanowski [=z Mustela africana stolzmanni],
Proc. Zool. Soc. London, for 1881, p. 835, November 15, 1881, is appUed to
the tropical weasel of the Upper Amazon Basin.

1881. jelskii (Mustela) Taczanowski [= Mustela frenata macrura], Proc.
Zool. Soc. London, for 1881, p. 647, May 17, 1881, was proposed for the female
in the mistaken opinion that it was specifically distinct from the larger male
which the same author previously had named macrura.

1891. arizonensis (Putorius) Meams [^Mustela frenata arizonensis]. Bull.
Amer. Mus. Nat. Hist., 3:234, June 5, 1891, until 1936 was applied to long-
tailed weasels of most of the western United States west of the Great Plains
but by restriction since 1936 has been appUed only to the animals in parts of
Arizona and New Mexico.

1894. peninsulae (Putorius) Rhoads [■:= Mustela frenata peninsulae], Proc.
Acad. Nat. Sci. Philadelphia, 1894:152, June 19, 1894, applies to the weasel of
central and southern Florida.

1896. alascensis (Putorius richardsonii) Merriam [= Mustela enninea alas-
censis], N. Amer. Fauna, 11:12, June 30, 1896, with type locality at Juneau,
Alaska, has been used for the ermine of southeastern Alaska ever since it was
proposed. In 1944 separate subspecific rank was accorded ermines on several
of the islands of southeastern Alaska which proportionately restricted the range
assigned to alascensis.

76 University of Kansas Publs., Mus. Nat. Hist,

1896, streatori (Putorius) Merriam [= Mustela erminea streatori], N. Amer.
Fauna, 11:13, June 30, 1896, applies to the ermine of the Pacific Coast from
Puget Sound, Washington, south nearly to the Golden Gate of California,

1896. arcticus (Putorius) Merriam [:= Mustela erminea arctica], N, Amer.
Fauna, 11:15, June 30, 1896. Ever since it was proposed, this name has been
applied to the subspecies of ermine of Alaska and the northern parts of Canada.

1896. kadiacensis ( [Putorius arcticus] ) Merriam [=z Mustela erminea kadia-
censis], N, Amer. Fauna, 11:16, June 30, 1896, is a valid name applied to the
ermine of Kodiak Island, Alaska.

1896. washingtoni (Putorius) Merriam [= Mustela frenata washingtoni], N.
Amer. Fauna 11:18, June 30, 1896, applies to the long-tailed vi'easel of the
southern Cascades of Washington and the northern Cascades of Oregon.

1896. saturatus (Putorius) Merriam [^= Mustela frenata saturata], N, Amer,
Fauna, 11:21, June 30, 1896, was little used until 1936 but apphes to long-tailed
weasel of hmited region in northern CaHfomia and southern Oregon.

1896, alleni (Putorius) Merriam [= Mustela frenata alleni], N. Amer.
Fauna, 11:24, June 30, 1896, applies to weasel of Black Hills region.

1896. oregonensis (Putorius xanthogenys) Merriam [z= Mustela frenata
oregonensis], N. Amer. Fauna, 11:25, June 30, 1896, apphes to long-tailed
weasel of parts of western Oregon and northern Cahfomia.

1896. goldmani (Putorius frenatus) Merriam [^= Mustela frenata goldmani],
N. Amer. Fauna, 11:28, June 30, 1896, appHes to the long-tailed weasel of
Chiapas, and parts of Guatemala and Salvador,

1896. leucoparia (Putorius frenatus) Merriam [= Mustela frenata leuco-
paria], N. Amer. Fauna, 11:29, June 30, 1896, applies to the long-tailed weasel
of Michoacan and Nayarit.

1896. tropicalis (Putorius) Merriam [— Mustela frenata tropicalis], N. Amer,
Fauna, 11:30, June 30, 1896, apphes to the long-tailed weasel of the Tropical
Life-zone of Veracruz.

1896. spadix (Putorius longicaudus) Bangs [= Mustela frenata spadix],
Proc. Biol. Soc. Washington, 10:8, February 25, 1896, apphes to the long-
tailed weasel of Minnesota and adjoining areas.

1896. rixosus (Putorius) Bangs [^= Mustela rixosa rixosa], Proc, Biol, Soc.
Washington, 10:21, February 25, 1896, apphes to the least weasel of Saskatche-
wan and adjoining areas and as the first available name for the species has been
used as the specific name for the species in America since 1896.

1897. paraensis (Putorius (Mustela) braziliensis) Goeldi [=: Mustela afri-
cana africana], Zool. Jahrb., abt. f. systematik, geogr. u. biol., 10:560, pi. 21,
September 15, 1897, a s>Tionym for the weasel of the lower Amazon area.

1898. neomexicanus (Putorius frenatus) Barber and Cockerell [= Mustela
frenata neomexicana], Proc. Acad. Nat. Sci. Philadelphia, p. 188, May 3, 1898,
apphes to the long-tailed weasel of New Mexico, Arizona, Durango and adjoin-
ing areas.

1898. haidarum (Putorius) Preble [= Mustela erminea haidarum], Proc,
Biol. Soc. Washington, 12:169, August 10, 1898, apphes to the ermine of the
Queen Charlotte Islands, British Columbia.

History of Classification 77

1899. notius {Putorius noveboracensis) Bangs [=Mustela frenata nove-
boracensis], Proc. New England Zool. Club, 1:53, June 9, 1899, was applied to
tlie long-tailed weasel of the Carolinas until 1936 since wliich time it has been
regarded as a synonym of noveboracensis.

1899. occisor (Putorius) Bangs [=Mustela frenata occisor], Proc, New
England Zool. Club, 1:54, June 9, 1899, applies to the long-tailed weasel of
central and northern Maine. Until 1936, occisor was ordinarily used as the
name of a full species but since then has been arranged as a subspecific name
under Mustela frenata.

1899. mundus (Putorius xanthogenijs) Bangs [= Mustela frenata munda],
Proc. New England Zool. Club, 1:56, June 9, 1899, is now applied, and gener-
ally has been since 1899, to the long-tailed weasel of the coastal district of Cali-
fornia north of San Francisco Bay.

1899. muricus (Putorius (Arctogale)) Bangs [= Mustela erminea muricus],
Proc. New England Zool. Club, 1:71, July 31, 1899, applies to the dimunitive
ermine, often erroneously designated least weasel, of the western United States.

1899. oribasus (Putorius (Arctogale) hmgicauda) Bangs [= Mustela frenata
oribasus], Proc. New England Zool. Club, 1:81, December 27, 1899, applies to
the long-tailed weasel of the Rocky Moimtains northward from Yellowstone
National Park.

1900. eskimo (Putorius rixosus) Stone [= Mustela rixosa eskimo], Proc.
Acad. Nat. Sci. Philadelphia, 1900:44, March 24, 1900, is appUed to the least
weasel of Alaska and adjacent parts of boreal North America.

1901. allegheniensis (Putorius) Rhoads [= Mustela rixosa allegheniensis],
Proc. Acad. Nat. Sci. Philadelphia, 1900:75, March 25, 1901, appUes to the
least weasel of the eastern United States.

1902. perdus (Putorius tropicalis) Merriam [= Mustela frenata perda],
Proc. Biol. Soc. Washington, 15:67, March 22, 1902, appHes to the long-tailed
weasel of the Lower Tropical Life-zone from southern Veracruz into Guatemala.

1903. microtis (Putorius) Allen [—Mustela erminea richardsonii]. Bull.
Amer. Mus. Nat. Hist., 19:563, October 10, 1903, is a name applied to an
individual ermine of small size from Shesley, British Columbia, which Allen
thought was specifically distinct from the ermine of the Hudsonian Life-zone
and adjacent territory. Now the name is arranged as a synonym of richardsonii.

1904. audax (Putorius) Barrett-Hamilton [= Mustela erminea arctica], Ann.
and Mag. Nat. Hist., ser. 7, 13:392, May, 1904. In the original description
the type locality. Discovery Bay, was erroneously stated to be in Greenland and
the name audax until 1945 was applied to the kind of weasel occurring in
northern Greenland whereas tlie type specimen was taken instead in northern
EUesmere Island and because the weasel there is subspecifically indistinguish-
able from ermines from farther west, audax is a synonym of Putorius arcticus.

1904. imperii (Putorius arcticus) Barrett-Hamilton [= Mustela erminea
richardsonii], Ann. and Mag. Nat. Hist., ser. 7, 13:392, May, 1904, based on an
animal from Fort Simpson, Mackenzie, Canada, proves to be inseparable from
richardsonii which has priority.

1904. polaris (Putorius arcticus) Barrett-Hamilton [= Mustela erminea
polaris], Ann. and Mag. Nat. Hist., ser. 7, 13:393, May, 1904, is the name used

78 University of Kansas Publs., Mus. Nat. Hist.

for the ermine of eastern Greenland and since 1945 has been used for the
weasel of Greenland as a whole.

1905. macrophonius (Putorius) Elliott [= Mustela frenata macrophonius],
Proc. Biol. Soc. Washington, 18:235, December 9, 1905, applies to the long-
tailed weasel of the mountains along the eastern border of Veracruz.

1906. leptus (Putorius streatori) Merriam [= Mustela erminea murica],
Proc. Biol. Soc. Washington, 16:76, May 29, 1903, until 1945 was applied to
the diminutive ermine of the Rocky Mountains from Wyoming south to northern
New Mexico but proves to be a synonym of muricus with type locality in the
Sierra Nevada of California.

1908. angustidens (Putorius cicognanii) Brown [=z Mustela erminea angus-
tidens], Mem. Amer. Mus. Nat. Hist., 9(pt. 4):181, pi. 17, is applied to an
extinct subspecies known from fossil remains of Pleistocene age from northern
Arkansas.

1908. gracilis (Putorius) Brown [= MusfeZa frenata gracilis], Mem. Amer.
Mus. Nat. Hist., 9(pt. 4): 182, 1908, apphes to a Pleistocene weasel known
from a single skull from northern Arkansas.

1912. costaricensis (Mustela) Goldman [^Mustela frenata costaricensis],
Proc. Biol. Soc. Washington, 25:9, January 23, 1912, apphes to the long-tailed
weasel of Costa Rica.

1913. primulina (Mustela) Jackson [^Mustela frenata primulina], Proc.
Biol. Soc. Washington, 26:123, May 21, 1913, appUes to the long-tailed weasel
of the central part of the United States in eastern Kansas and adjoining areas.

1913. campestris (Mustela) Jackson [= Mustela rixosa campestris], Proc.
Biol. Soc. Washington, 26:124, May 21, 1913, applies to the least weasel of
the Great Plains region.

1913. olivacea (Mustela peninsulae) HoweU [:= Mustela frenata olivacea],
Proc. Biol. Soc. Washington, 26:139, May 21, 1913, applies to the long-tailed
weasel of the southeastern United States excepting most of Florida.

1914. meridana (Mustela) HoUister [= Mustela frenata 7neridana], Proc.
Biol. Soc. Washington, 27:143, July 10, 1914, applies to the long-tailed weasel
of northern South America.

1916. nicaraguae (Mustela tropicalis) Allen [= Mustela frenata nicarguae].
Bull. Amer. Mus. Nat. Hist., 35:100, April 28, 1916, appUes to the long-tailed
weasel of Nicaragua.

1927. arthuri (Mustela noveboracensis) Hall [z= Mustela frenata arthuri],
Proc. Biol. Soc. Wasliington, 40:193, December 2, 1927, applies to the long-
tailed weasel of Louisiana and adjoining areas.

1932. semplei (Mustela arctica) Sutton and Hamilton [= Mustela erminea
semplei], Ann. Carnegie Mus., 21(2) :79, February 13, 1932, originally was
appUed to the ermine of Southampton Island but after 1945 was appHed also
to the ermine of Baffin Island, Melville Peninsula and the west side of Hudsons
Bay as far south as Eskimo Point.

1932. panamensis (Mustela frenata) Hall, Proc. Biol. Soc. Washington,
45:139, September 9, 1932, applies to the long-tailed weasel of Panamd.

History of Classification 79

1932. anguinae {Mustela cicognanii) Hall [^Mustela erminea anguinae],
Univ. California Publ. Zool., 38:417, November 8, 1932, applies to the ermine
of Vancouver Island, British Columbia.

1935. labiata (Mustela arctica) Degerb0l [^Mustela erminea semplei].
Kept. 5th Thule Exped., 1921-1924, vol. 2, no. 4, p. 25, 1935. When Degerb0l
wrote his description and proposed this name he was unaware that Sutton
and Hamilton had three years before based a new name on weasels from
Southampton Island. Because the two names apply to the same subspecies,
Degerb0rs name, labiata, must fall as a synonym of semplei which has priority.

1935. helleri (Mustela frenata) Hall, Proc. Biol. Soc. Washington, 48:143,
August 22, 1935, applies to the long-tailed weasel of eastern Peru.

1936. nevadensis (Mustela frenata) Hall, Carnegie Inst. Washington, publ.
no. 473, p. 91, November 20, 1945, applies to the long-tailed weasel of the
western United States. For many years, animals of this subspecies were re-
ferred to longicauda and from 1891 until 1936 to arizonensis.

1936. effera (Mustela frenata) Hall, Carnegie Inst. Washington, publ. no.
473, p. 93, November 20, 1945, apphes to the long-tailed weasel of the Blue
Mountains region. From 1891 until 1936 this animal was referred to under the
name arizonensis.

1936. altifrontalis ( Mustela frenata ) Hall, Carnegie Inst. Washington, publ.
no. 473, p. 94, November 20, 1936, applies to the long-tailed weasel of the
humid coastal district from Puget Sound southward into Oregon.

1936. nigriauris (Mustela frenata) Hall, Carnegie Inst. Washington, pubL
no. 473, p. 95, November 20, 1936, applies to the long-tailed weasel of the
coastal district of California from San Francisco Bay southward to Point Con-
cepcion. Previous to 1936, xanthogenys was the name applied to this race of
weasel.

1936. latirostra (Mustela frenata) Hall, Carnegie Inst. Washington, pubL
no. 473, p. 96, November 20, 1936, applies to the long-tailed weasel of southern
California which previously had borne the name xanthogenys.

1936. pulchra (Mustela frenata) Hall, Carnegie Inst. Washington, publ.
no. 473, p. 98, November 20, 1936, is applied to the long-tailed weasel of the
southern end of the San Joaquin Valley of California.

1936. inyoensis (Mustela frenata) Hall, Carnegie Inst. Washington, publ.
no. 473, p. 99, November 20, 1936, is applied to the long-tailed weasel of
Owens Valley, California.

1936. texensis (Mustela frenata) Hall, Carnegie Inst. Washington, publ.
no. 473, p. 99, November 20, 1936, applies to the long-tailed weasel of central
Texas which previously had been assigned to the subspecies frenata.

1936. perotae (Mustela frenata) Hall, Carnegie Inst. Washington, publ.
no. 473, p. 100, November 20, 1936, applies to long-tailed weasel of the
mountains along the Puebla-Mexico boundary.

1938. boliviensis (Mustela frenata) Hall, Proc. Biol. Soc. Washington,
51:67, May 18, 1938, applies to the southernmost known long-tailed weasel
which is in the Lake Titicaca region in Peru and Bolivia.

80 University of Kansas Publs., Mus. Nat. Hist.

1944. salva (Mustela erminea) Hall, Proc. Biol. Soc. Washington, 57:35,
June 28, 1944, applies to the ermine of Admiralty Island, southeastern Alaska.

1944. initis {Mustela erminea) Hall, Proc. Biol. Soc. Washington, 57:37,
June 28, 1944, applies to the ermine of Baranof and Chichagof islands, south-
eastern Alaska.

1944. celenda (Mustela erminea) Hall, Proc. Biol. Soc. Washington, 57:38,
June 28, 1944, applies to the ermine of Prince of Wales, Dall and Long is-
lands, Alaska.

1944. seclusa (Mustela erminea) Hall, Proc. Biol. Soc. Washington, 57:39,
June 28, 1944, applies to the ermine of Suemez Island, southeastern Alaska.

1945. invicta (Mustela erminea) Hall, Jour. Mamm., 26:75, February 27,
1945, applies to the ermine of the Rocky Mountains for several hundred miles
both north and south of the United States-Canadian boundary.

1945. fallenda (Mustela erminea) Hall, Jour. Mamm., 26:79, February 27,
1945, appUes to the ermine of the coastal mainland in southern British Columbia
and northern Washington.

1945. olympica (Mustela erminea) Hall, Jour. Mamm., 26:81, February 27,
1945, applies to the diminutive ermine of the Olympic Peninsula, state of
Washington.

1945. gulosa (Mustela erminea) Hall, ]oui. Mamm., 26:84, February 27,
1945, applies to the diminutive ennine of the Cascades in Washington.

1945. bangsi (Mustela erminea) Hall, Jour. Mamm., 26:176, July 19, 1945,
is the name apphed today to the ermine of the western Great Lakes region.

In 1925 when this study was begun, the American weasels (subgenus Mus-
tela proper) were arranged as belonging to 47 kinds (including subspecies)
of 29 full species. In the present account a total of 68 kinds, belonging to 4
full species are recognized in the subgenus Mustela. The increase in nxmiber
of subspecies and the decrease in number of species are the nomenclatural
results ordinarily obtained in this decade from a systematic study of a genus
of American mammals.

MUSTELA 81

CHECK-LIST OF AMERICAN SPECIES AND SUBSPECIES

OF THE GENUS MUSTELA

Subgenus MUSTELA Linnaeus

PAGE

Mustela erminea 87

Mustela erminea arctica (Merriam) 96

Mustela erminea polaris (Barrett-Hamilton) 103

Mustela erminea semplei Sutton and Hamilton 105

Mustela erminea kadiacensis ( Merriam ) 108

Mustela erminea richardsonii Bonaparte 110

Mustela erminea cicognanii Bonaparte 118

Mustela erminea hangsi Hall 124

Mustela erminea invicta Hall .- 128

Mustela erminea alascensis ( Merriam) 131

Mustela erminea salva Hall 135

Mustela erminea initis Hall 136

Mustela erminea celenda Hall 139

Mustela erminea seclusa Hall 141

Mustela erminea haidarum (Preble) 142

Mustela erminea anguinae Hall 145

Mustela erminea fallenda Hall 148

Mustela erminea olympica Hall 153

Mustela erminea streatori ( Merriam) 155

Mustela erminea gulosa Hall 159

Mustela erminea muricus ( Bangs) 161

MuMela erminea angustidens ( Brown) 165

Mustela rixosa 168

Mustela rixosa eskimo Stone 181

Mustela rixosa rixosa Bangs 184

Mustela rixosa allegheniensis Rhoads 187

Mustela rixosa campestris Jackson 190

Mustela frenata 193

Mustela frenata noveboracensis (Emmons) 222

Mustela frenata occisor ( Bangs ) 230

Mustela frenata primulina ( Jackson ) 232

Mustela frenata arthuri Hall 241

Mustela frenata olivacea Howell 244

Mustela frenata peninsulae Rhoads 250

Mustela frenata spadix ( Bangs ) 252

Mustela frenata longicauda Bonaparte 262

Mustela frenata oribasus ( Bangs ) 270

Mustela frenata alleni ( Merriam ) 274

Mustela frenata arizonensis ( Meams) 276

Mustela frenata nevadensis Hall 280

Mustela frenata effera Hall 291

Mustela frenata washingtoni (Merriam) 294

Mustela frenata saturata ( Merriam ) 297

Mustela frenata altifrontalis Hall 300

Mustela frenata oregonensis (Merriam) 304

Mustela frenata munda ( Bangs ) 3C9

82 University of Kansas Publs., Mus. Nat. Hist.

PACE

Mustela frenata xanthogenys Gray 315

Mustela frenata nigriauris Hall 319

Mustela frenata latirostra Hall 323

Mustela frenata pulchra Hall 328

Mustela frenata inyoensis Hall 331

Mustela frenata neomexicana (Barber and Cockerell) 333

Mustela frenata texensis Hall 338

Mustela frenata frenata Lichtenstein 341

Mustela frenata leucoparia ( Merriam ) 347

Mustela frenata perotae Hall 351

Mustela frenata goldmani ( Merriam ) 355

Mustela frenata macrophonius ( Elliot ) 360

Mustela frenata tropicalis ( Merriam ) 363

Mustela frenata perda ( Merriam) 366

Mustela frenata nicaraguae Allen 370

Mustela frenata costaricensis Goldman 372

Mustela frenata panamensis Hall 375

Mustela frenata meridana Hollister 379

Mustela frenata affinis Gray 384

Mustela frenata aureoventris Gray 387

Mustela frenata helleri Hall 391

Mustela frenata agilis Tschudi 393

Mustela frenata macrura Taczanowski 398

Mustela frenata holiviensis Hall 402

Mustela frenata gracilis ( Brown ) 404

Subgenus Gramnogale Cabrera

Mustela africana 406

Mustela africana africana Desmarest 409

Mustela africana stolzmanni Taczanowski 413

Subgenus Putorius Cuvier

( Black-footed Ferret — not treated in present work )

Mustela nigripes ( Audubon and Bachman )

Subgenus Lutreola Wagner

(Minks — not treated in present work)
Mustela vison

Mustela vison vison Schreber
Mustela vison mink Pcale and Beauvois
Mustela vison lutensis (Bangs)
Mustela vison evergladensis Hamilton
Mustela vison vulgivaga ( Bangs )
Mustela vison letifera Hollister
Mustela vison lacustris (Preble)
Mustela vison energumenos (Bangs)
Mustela vison evagor Hall
Mustela vison aestuarina Grinnell
Mustela vison nesolestes (Heller)
Mustela vison melampelus (Elliot)
Mustela vison ingens (Osgood)
Mustela macrodon (Prentiss)

iJ

MUSTELA 83

ARTIFICIAL KEY TO AMERICAN SPECIES OF THE

GENUS MUSTELA

PAGB

A Length of upper tooth-rows less than 20 mm. in males and 17.8 mm, in
females.

B Postglenoid length of skull more than 47 per cent of condylo-
basal length.

C Tail without a black pencil and with at most a few black
hairs at extreme tip; in both sexes mastoid breadth or-
dinarily exceeds breadth of braincase,

Mustela rixosa, least weasel, p. 168

C Tail with a black pencil; in females mastoid breadth or-
dinarily exceeded by breadth of braincase,

Mustela erminea, ermine, p. 87

B' Postglenoid length of skull less than 47 per cent of condylobasal
length.

D Tail with distinct black tip; midventral line white,
yellowish, orange, not same color as upper parts; p2

present; thenar pad on forefoot absent,

Mustela frenata, long-tailed weasel, p. 193

D' Tail without black tip; midventral line same color as
upper parts; p2 absent; thenar pad on forefoot present,

Mustela africana, tropical weasel, p. 406

A' Length of upper tooth-rows more than 20 mm. in males and 17.8 mm. in
females.

E Abdomen all white; face with blackish mask; ml lacking even a
trace of a metaconid; distance between upper canines more
than width of basioccipital as measured between foramina sit-
uated midway along medial sides of tympanic bullae,

Mustela nigripes, black-footed ferret.

E' Abdomen dark brov^Ti, like back; face uniformly brown without
blackish mask; ml with incipient metaconid; distance between
upper canines less than width of basioccipital as measured
between foramina situated midway along medial sides of tym-
panic bullae, Mustela vison, mink, American mink.

DIAGNOSIS OF THE GENUS

Genus Mustela Linnaeus
Weasels, Ferrets, Polecats, Minks

Genotype. — Mustela erminea Linnaeus.

Diagnosis. — Legs short; body relatively long; adults 190 mm. to
700 mm. in total length; skull ranging in basilar length from 16 to 70
mm.; facial angle slight; tympanic bullae greatly inflated (moder-
ately in Lutreola), cancellous, and with paroccipital processes
closely appressed to bullae; palate behind upper molars; dental

r , I 3 C 1 P 2-3 M 1 . . r xt-i 1 i

formula: —'—'—'—'—' -rr'' ~' ~Z' mner moiety of Ml larger than

i3clp3-2m2 ^ °

outer; P4 with simple deuterocone; in ml trigonid longer than

84 University of Kansas Publs., Mus. Nat. Hist.

talonid, metaconid absent (incipiently developed in Lutreola), and
talonid trenchant.

For many years prior to 1911, the name Mustela was appHed to
martens, and Putoritis was regarded as the first available generic
name for the weasels. In 1911 Thomas (1911:139) showed that M.
erminea ( Mustela of Gesner ) by tautonymy was the type of Mustela
and subsequently the generic name Mustela has been used for the
true weasels which include the American weasels to which we now
apply the specific names erminea, rixosa and frenata. The mink,
Mustela (Lutreola) vison, and the black-footed ferret, Mustela
(Putorius) nigripes, since 1911 also have been referred by most
American authors to the genus Mustela, the names Lutreola and
Putorius being regarded by these authors as having no more than
subgeneric status. European writers, on the other hand, accord
greater taxonomic weight to the zoological differences between fer-
rets and weasels and, therefore, accord full generic rank to Putorius.
Consequently, for the black-footed ferret, Europeans today write
Putorius nigripes and Americans write Mustela nigripes. For the
same reasons, the name of the mink is written by some European
zoologists Lutreola vison and by American zoologists Mustela vison.

EXPLANATION OF SYSTEMATIC TREATMENT

For each full species there will be found under the account of it the follow-
ing information: Type, statement of geographic range, selected characters for
ready recognition, other characters of the species, a summary of geographic
variation, and information on habits, in the order mentioned.

For each subspecies, information is presented in the following order: earliest
available zoological name, synonyms, type, geographic range, zoological char-
acters for ready recognition, description (mentioning size, certain external
features including color, the skull and teeth) historical material when war-
ranted, remarks which may elaborate on points made in preceding paragraphs,
and other information thought to be useful, and finally a Ust of specimens
e.xamined.

In explanation of certain of these categories it should be said that in the
synonymy no attempt is made to hst every published reference to the subspecies
concerned. It is aimed, however, to include at least one citation to each name-
combination that has been applied, to the subspecies concerned, along with
other especially important references. Mere records of occurrence are not re-
garded as especially important and citations to them ordinarily are omitted in
the synonymy. No comma is placed between the zoological name and the
name of the author who coined and first used the name in accordance with the
rules of zoological nomenclature. Otherwise a comma is interposed between
the zoological name and the name of tlie user (author). When the accepted
(earliest available) name of a subspecies at the head of any one of the follow-
ing accounts is combined with a generic name different from that with which

MUSTELA 85

it originally was placed, the authority for the name is set in parentheses. The
same rule is followed with the name of a full species when it is written without
any subspecific name following. Parentheses in such situations, therefore, de-
note that for the terminal part of the scientific name there has been a change
in generic name with which the terminal part of the scientific name is here
associated.

In the paragraph headed "characters for ready recognition", only a few
characters, namely, those regarded as most useful for identification when the
student has limited time, are mentioned. Other features useful for distinguish-
ing the kind of animal in question from its near relatives are to be found in the
description and comparisons.

In the description, external measurements, unless otherwise indicated, are
those recorded by tlie collector on the label attached to the skin. Total length
is the distance from the tip of the pad on the nose to the tip of the fleshy part
of the tail when the relaxed animal is laid out straight, not stretched. This
measurement does not include the hairs that project beyond the end of the
fleshy part of the tail. Length of tail is the distance from the base of the tail,
when it is bent at right angles to the long axis of the body, to the tip of tlie
fleshy part of the tail excluding the hairs that project beyond the fleshy part
of the tail. Length of tail and length of tail-vertebrae are synonymous. Length
of hind foot is measured from the proximal end of the calcaneum to the tip of
the longest claw.

Capitalized color terms, unless otherwise indicated, refer to Ridgway's
(1912) Color Standards and Color Nomenclature. Some use is made of color
terms taken from Oberthiir and Dauthenay (1905) because those authors show
a much larger number of shades between dark brown and black than does
Ridgway (1912). The colors of the upper parts of most weasels are some
shade or other of dark brown. Color terms that do not have the initial letter
capitalized do not refer to any one standard and consequently are used in a
general sense.

Relative extents of the color of the upper parts and underparts are computed
from measurements of the circumference of the body at the place where the
color of the underparts is narrowest. Ordinarily this place is in the lumbar
region rather than in the thoracic region.

An explanation of how cranial measurements were taken is given on page
417. In designating teeth, capital letters are used for teeth in the upper jaw
and lower case letters are used for teeth in the lower jaw. For example: 12
denotes the second incisor tooth in the upper jaw and i2 denotes the second in-
cisor tooth in the lower jaw; CI and cl refer to the canine tooth of the upper
jaw and lower jaw, respectively; P3 and p3 refer to the third premolar of the
upper jaw and lower jaw, respectively, bearing in mind that the first (anterior)
premolar is absent in the lower jaw and upper jaw of weasels (see fig. 31 on
page 416), as also, in some kinds of weasels, is the second premolar; Ml and
ml refer to the first molar of the upper jaw and lower jaw respectively.

In describing the skull and teeth the two sexes are treated separately
because difi^erences in shape as well as size are the rule. Unless otherwise
indicated, the skulls on which descriptions are based are of adults. Weights
of skulls include the weight of the lower jaws. In general, every second sub-
species is described. For a subspecies geographically next adjacent to the

86 University of Kansas Publs., Mus. Nat. Hist.

one described, only the diflFerences between the two are enumerated. Fhi*
method of description indicates also likenesses and is more economical of words
than some other methods of description. Also, by use of this method, cross
reference is reduced to one other subspecies. Following this formal descrip-
tion, there is a comparison of the cranial and dental characters with those of
geographically adjacent subspecies.

In the paragraph headed "Remarks" the two words "character" and
"structure" frequently appear. The word structure here is used to mean some
part of an animal, as for example, a hair, a muscle, a bone, or an internal organ.
A structure is not a system, as for example, the digestive system or osseus
system. A character is some weight, linear dimension, volume, shape, color,
or other perceptible attribute of a structure, of a system, or of an entire
organism.

In recording the localities of capture of specimens examined, effort has
been made to be exactly as precise as the locality data on the labels of the
specimens permit. The word "County" is written out in full when the name of
the county is written on the label of each specimen listed from that county.
When one specimen, or more, here assigned to a given county lacks the name
of the county on the label, then the abbreviation "Co." is used. The sur-
prising frequency with which the same place name is repeated in a given state
or province makes it desirable for the collector to write the name of the
county, or corresponding minor political subdivision, on labels of study speci-
mens at the time they are prepared.

MUSTELA ERMINEA 87

SYSTEMATIC ACCOUNTS OF SPECIES AND SUBSPECIES

MUSTELA ERMINEA Linnaeus

Emiine

( Synonymy under subspecies )

Type. — Mustela erminea Linnaeus, Systema Naturae, 10th ed., p. 46, 1758.

Range. — From tlie British Isles and Atlantic Coast of Europe across Eiurasia
and North America including Greenland, from the northernmost land, south,
in North America, to the lower margin of the Canadian Life-zone; geographi-
cally south to Connecticut, New York, Pennsylvania, northeastern Ohio, south-
em Michigan, Wisconsin, northern Iowa, Minnesota, North Dakota, in the
Rocky Mountains to northern New Mexico, in the Sierra Nevada to Mono
County, Cahfomia, and on the Pacific Coast to the Golden Gate.

Characters for ready recognition. — Differs from Mustela rixosa in
presence of black pencil on tail, tail-vertebrae more than a fourth
of length of head and body, and in regions where the two species
occur togetlier, basilar length of skull more than 32.5 in males and
more than 31.0 in females; from Mustela frenata, in regions where
the two species occur together, by tail less than 44 per cent of length
of head and body and by postglenoidal length of skull more than
46 per cent of condylobasal length in males and more than 48 per
cent in females.

Characters of the species. — Size medium to small (total length
225 to 340 mm. in males and 190 to 290 mm. in females); tail 30
to 45 per cent of length of head and body, with distinct black
pencil; caudal vertebrae 16 to 19; skull with long braincase and
short precranial portion; postglenoidal length, when expressed
as a percentage of the condylobasal length, more than 48 in females
and ordinarily more than 46 in males; upper parts brown; under-
parts whitish, ordinarily continuous from chin to inguinal region
but in subspecies in the humid region along the Pacific Coast inter-
rupted in some individuals by brown of upper parts encircling body
in the abdominal region. The soles of the feet in each of the sub-
species are densely haired in winter and have only a relatively small
area of the foot-pads exposed in summer, the intervening areas
being well haired even at that season. The uniformity throughout
the species as regards hairiness of the foot-soles and also the char-
acter of the vibrissae makes it unnecessary to describe these features
in the accounts of the subspecies of erminea.

Geographic variation. — In the Old World 16 or more subspecies
are currently recognized and there are 20 in North America. The
features in which geographic variation is especially prominent are:

88 UNivERSiTi' OF Kansas Publs., Mus. Nat. Hist.

First, size, as expressed by external measurements and weight,
second, color pattern, depending on the extent, in relation to one
another, of the dark-colored upper parts and light-colored under-
parts, and third, breadth and depth of the rostral region of the
skull. Except in size, the variation in the skull is less than in M.
frenata. Likewise in tone and shade of upper parts and hue or tint
of underparts, erminea is less variable than frenata and has the face
all of one color without the contrasting color-pattern of the face
and head seen in many subspecies of frenata. M. erminea exceeds
frenata as regards variation of the size of the area occupied by tlie
light-colored underparts. At one extreme is the subspecies arctica
in which the area of the light color extends well up on the sides of
the body, down the insides of the legs, over the feet and far out
on tlie lower side of the tail whereas at the other extreme are the
races streatori and olympica in which the light-colored underparts
are restricted to two areas, one on the chin, throat and chest, and
the other on the inguinal region. These areas may or may not be
connected by a thin line of white color along the midline of the
underparts. In size of animal, erminea probably exhibits the maxi-
mum variation among American species of weasels; an average-
sized male of the race arctica weighs 4 times as much as one of the
race muricus, and in the species frenata I doubt that the difference
is quite as great between individuals of the smallest race, effera,
on tlie one hand, and either of the largest races, texensis or macro-
phonius, on the other hand although actual weights are not avail-
able for these races of frenata. As elsewhere indicated, the small-
sized individuals of M. erminea are of the southern races and the
large-sized individuals are of the northern races. This decrease in
size southward occurs both in Asia and in America.

Natural history — habitat and numbers. — Along the International
Boundary east of the Turtle Mountains, Soper (1946:136) found
this species present only in timbered areas and absent from many
untimbered areas. Of the same species to the westward he com-
ments "so far as I know at present, there is no evidence to show
that any short-tailed weasels inhabit a broad strip of treeless terri-
tory immediately north of the International Boundary in Canada
from southwestern Alberta to southeastern Saskatchewan". The
same author (1942) reports that in the general area of Wood Buf-
falo Park, Northwest Territory, south of Great Slave Lake, the
ermine is uncommon on pine-grown sand ridge and rolling upland
and common in lower spruce-aspen parklands, stream-side conifer-
ous belts, and grassy, semi-wooded swamplands.

MUSTELA ERMINEA 89

Nine ermines per square mile is the number that Soper (1919:46-
47) estimated at Edmonton on the basis of the numbers that he
trapped there in the winters of 1912-13 and 1913-14 and on the basis
of the tracks of remaining ermines. From corresponding data he
estimated the population in the winter of 1913 on the Hay River,
north of Jasper Park, to be nine per square mile. In each of these
instances he estimated ten weasels per square mile but he inclined
to the view that one-tenth of the animals involved in his counts
were long-tailed weasels (Miistela frenata). Osgood (1909B:30)
and his field companion in the period July 31 to September 3, 1903,
took a series of 42 specimens within a radius of 500 yards of their
camp at the head of Seward Creek, Alaska, all caught in four traps,
in one month. Of the 42 specimens, 28 are males and 14 are fe-
males.

Fluctuations of a multiannual nature are marked in this species.
Bailey (1929:156) observes that in Sherburne County, Minnesota,
when meadow mice are abundant for two or three years these
weasels become abundant but that when the mice are scarce the
weasels also become scarce. Manning (1943:56), on Southampton
Island, noted "that the maximum and minimum points of the weasel
cycle are much more sharply marked than those of the fox cycle
and the increase and decrease are more rapid."

How far an ermine will travel in a given length of time has sel-
dom been recorded but Hamilton (1933:293), on March 20, 1932,
"followed the track of a small weasel, presumably a male cicognanii,
for four miles in the fresh snow", and Ingles (1942) observed a
diminutive ermine of the subspecies M. e. mnricus, at Woods Lake,
California, 286 yards from its den.

Behavior

As regards locomotion, Soper (1919:46), in reference to Mustela
cicognanii, presumably in Ontario, Canada, writes that in the
bounding gait the hind feet register almost, if not exactly, in the
front-foot impressions, with the right front and hind feet lagging
shghtly behind. "The distance normally is about 19 inches, repre-
senting a regular rate of travel. ... In traversing open spaces
they resort to long, graceful leaps upwards of six feet in length.
. . . I measured a record ... of 8 feet, 2 inches."

Of M. e. arctica. Dice (1921:22) writes that when it runs "the tail
is carried off the ground usually at an angle of about 45 degrees."
Seton (1929 (2):598) states that "At Carberry [Manitoba] I have
often seen this energetic little creature seeking for Mice in the deep.

90 University of Kansas Publs., Mus. Nat. Hist.

soft snow. Its actions are much like those of an Otter pursuing sal-
mon. Sometimes it gallops along a log, or over an icy part of the
drift; then plunges out of sight in a soft place, to reappear many
yards away. . . ."

Little is recorded concerning swimming but on this score Seton
(1929 (2) :602) does quote J. W. Curran, who in July, 1899, at Lake
Couchiching, Ontario, watched an ermine pursue a chipmunk into
the water and for 100 yards before giving up the chase and wheeling
around and making for shore. In swimming "The Weasel, I think,
showed more of his body, and seemed to exert himself more" than
the chipmunk.

As to voice. Dice (1921:22), at Tanana, Alaska, heard the ermine,
when excited, bark somewhat like a mink but not so loud and Seton
(1929 (2):606) quotes Manley Hardy to the effect that the species
has a purring note.

Sense of smell was used by an M. e. muricus that Dixon (1931:72)
watched as the ermine followed a three-fourths-grown pika. Con-
cerning the ermine at Carberry, Manitoba, Seton (1929 (2):598-
599) writes that "The smell of blood must be as far-reaching as it
is attractive to these sanguinary little creatures. I have frequently
hung new-killed Rabbits and partridges temporarily in trees, and,
after an absence, in some cases of a few minutes only, have found
an Ermine mauling the game, though there was no sign of such a
visitor when the cache was made."

Enemies

George Measham, of Winnipeg, found sign in the snow indicating
that a great snowy owl had killed an ermine and T. Mcllwraith
shot a bald eagle at Hamilton Bay which had the bleached skull
of a weasel ( probably of this species ) clinging to the tliroat ( Seton,
1929 (2):603).

A. B. Howell (1943:98) hkens mustehd mammals to domestic
cats in their manner of crossing roads and thinks that mustelids
loiter at the side of the road until the stimulus of the approaching
car causes them to make a dash whereupon they are caught by the
wheels and killed. Three of four weasels seen to cross the road
were killed, one even having apparently crossed the road before
turning back and being killed under the car. One weasel killed was
Mustela erminea cicognanii. Dalquest (1948:190) in writing of
this species in the state of Washington, says "I have seen only one
abroad in the daytime. It dashed from a roadside thicket . . .
and was crushed beneath the wheels of a car."

MUSTELA ERMINEA 91

Food

The killing of prey is described by Hamilton (1933:332) as fol-
lows: "A rapid dash, and the bird or mouse is grabbed over the
back of the skull, the fore legs encircle the animal as though hugging
it, and the hind legs are brought up to scratch wildly at the captive.
. . . If [the prey is] a large animal, as a rat, the weasel usually
Hes on its side, while the diminishing struggles of the rodent con-
tinue, but if a mouse or a small bird [is the object of attack], the
weasel is apt to crouch over its prey. Little time is lost over the
first [mouse] ... if two mice are present [;] a strong bite
through the brain case . . . [is] sufficient. If only one animal
is present, the weasel dawdles over its kill some time after life has
departed."

Hamilton's (1933:333) study of the contents of the digestive
tracts of bodies of ermines obtained from fur trappers and fur buy-
ers in New York enabled him to publish the following "Frequency
Indices of Mammal Genera in Fall and Winter Food of 191 Mustela
cicognanii": Microtus, 35.7 per cent; mammals undetermined to
genus but principally mice, 16.3; Blarina, 15.1; Peromyscus, 11.4;
Sylvilagus, 9.0; Sorex, 4.9; Rattus, 4.4; Tamtas, 3.6. Close corre-
spondence is shown by the following data of Aldous and Manweiler
(1942) for the ermine from Lake of the Woods, Minnesota: mice,
58.7 per cent by number and 54.5 by volume; shrews 22.5 and 21.8
per cent; birds, 2.7 and 5.0 per cent. Of the mice in stomachs, 40
per cent were microtines, 15 per cent were Peromyscus and 45 per
cent were unidentified as to kind. Fragments of a small fish were
found in one stomach. Summed up, the dominant winter foods
were mice and shrews. Trapping of the mammal populations was
done to see what the available food was and it was found that the
small mammals were eaten in direct ratio to their relative abun-
dance. Snowshoe rabbits and red squirrels were not eaten. The
Minnesotan data were from 60 stomachs and 53 intestinal tracts re-
covered from 129 weasels trapped by use of scent ( not bait ) mostly
from January 1 to February 7, 1939, although a few were trapped
in 1938. Analyses of contents from stomachs gave approximately
the same results as those from intestines. In 1939 at Lake of the
Woods, weasels were concentrated where food was abundant but
no such concentration was noted in the following winter.

Big short-tailed shrew (Blarina brevicauda). — In New York State,
the ermine preys on Blarina as shown by Hamilton's (1933:330)
seeing one being carried by a male ermine on May 6, 1931, and
another being carried by a female on May 13, 1932. The same

92 University of Kansas Publs., Mus. Nat. Hist.

author (1928:249) found the remains of a Blarina in a small female
from Malone, New York. Kirk (1921) observed, however, that
the ermine ( M. e. cicognanii ) avoided the shrew, Blarina, caught in
a trap and that Blarina avoided the weasel caught in a trap.

Chipmunk (genus Tamias). — Remains were found in a male
ermine in New York on May 14, 1932 (Hamilton, 1933:330), and
Seton (1929 (2):602) records a chipmunk at Lake Couchiching,
Ontario, that was pursued into the water by an ermine.

Deer mice (genus Peromyscus) . — As shown by Hamilton (1933:
33) and Aldous and Manweiler (1942), Peromyscus was second
only to microtines in numerical abundance among the food items
of ermines in New York and Minnesota. Peromyscus and micro-
tine rodents were brought to a den of the dimunitive M. e. muricus
in early August, in Fresno County, California, according to Ingles
(1942). He observed that an Alpine chipmunk was active under
and around the tree and that juncos reared young 40 feet from the
den but that the chipmunk and juncos were unmolested by the er-
mines.

Lemming (genus Lemmus). — One was recovered from a female
ermine ( with milk in her glands ) at Laurier Pass, British Columbia
(Sheldon, 1932:201).

Red-backed mouse (genus Clethrionomys) . — Criddle and Criddle
( 1925:146) record that on "May 31, 1921. — Saw a Bonaparte's weasel
capture a Red-backed Vole after a long hunt during which the
pursuer never once lost track of its victim."

Meadow mice (genus Microtiis). — As shown by the data of
Hamilton (1933:333) and Aldous and Manweiler (1942) recorded
above, Microtus is the item of first importance in the diet of the
ermine in New York and Minnesota. Criddle and Criddle (1925:
146) write concerning the vicinity of Treesbank, Manitoba, that
"October, 1918. — Following a severe outbreak of mice in 1916-17,
Bonaparte's weasel increased enormously and very soon reduced
the rodents to comparative rarity. This resulted in a scarcity of
food for the weasels, which in their turn became greatly reduced
in numbers."

Old World rat {Ratt us). —Bishop (1923) found two headless rats
near a nest of this species in Albany, New York.

Pika (Ochotona). — Dixon (1931:72) at Milner Pass, Colorado,
on July 20, 1931, saw an ermine, of the subspecies muricus, follow-
ing a three-fourths grown pika by scent and outrunning the pika.
The pikas worked a relay system and the weasel abandoned the
trail when the fourth pika became the object of the chase.

MUSTELA ERMINEA 93

Cottontail (genus Sylvilagus). — Hamilton (1933:33), as noted
above, found remains of cottontail in the digestive tracts of ermine
that had been trapped for fur in winter. Possibly these remains
were bait that had been placed at traps.

Snowshoe rabbit (Lepus americanus). — Morse (1939:210) in a
study of predation on hares and grouse in the period of notable deci-
mation of these two game species in 1935-1936 in the Cloquet Valley
State Forest, in St. Louis County, Minnesota, found that "weasel
predation on hares appeared to be of very low incidence or alto-
gether lacking."

Wild birds (Class Aves). — Aldous and Manvv^eiler (1942), as
noted above, found that the remains of birds constituted five per
cent by volume of the food of the ermine in winter in Minnesota.

Chicken (genus GaZ/w5 ) .— Criddle and Criddle (1925:145), who
published relatively extensive data on the tiiree species of weasels
of Manitoba, write that: "We have no record of Bonaparte's weasel
killing poultry, and we doubt whether it ever does so." However,
Soper (1919:46) investigated the excited cackling of a hen brooding
chicks at night and found a solitary ermine that had killed three
chicks and that had tiie remainder under very active scrutiny.

Leopard frog (Rana pipiens). — One frog was found in a male
ermine on November 20, 1931, in New York by Hamilton (1933:
300).

Fish (Class Pisces). — Aldous and Manweiler (1942) found frag-
ments of a small fish in one of 60 stomachs of ermine from Minne-
sota.

Earthworm (Phylum Annelida). — Osgood (1936:64), presum-
ably at Rutland, Vermont, observed a pair of weasels from 2:15
P. M. to 5:00 P. M., in a barn and saw the female in that time make
many trips for food for her young. Only earthworms were brought.
Fifty traps in an adjacent, swampy field caught only one bull frog
and no mice indicating that mice had been eliminated from the
foraging territory of the ermine.

In handling food, Dice (1921:22) noted that the Alaskan ermine
did not use the feet but only the mouth.

Reproduction

Litters of 4, 4, 7, 7, and 8, yielding an average of 6 young per
litter have been recorded from the northeastern United States by
Hamilton (1933:327). He {op d^ : 321-325) described animals
one day old from New York State as being flesh-colored, having the
long neck of tlie adult and a fine growth of white hair two milli-

94

University of Kansas Publs,, Mus. Nat. Hist.

meters in length, on the dorsal surface of the neck, that foreshadows
the mane or pompadour that is prominent from the 14th to the 21st
day of hfe. Six animals, when one day old averaged 1.7 grams in
weight, which was three per cent of the weight of an adult female
and one and one half per cent of the weight of an adult male. At
two weeks of age the heavy brown mane stood out in marked
contrast to the rest of the scantily, white-furred animal. The eyes
opened on the thirty-fifth day of life.

.^^-^-'^.

Fig. 24. Mustela erminea richard-
sonii, adult female. Catalogue Number
14866, U. S. Nat. Mus., Fort Chimo,
Ungava. X ^■

Ventral view of body of a pregnant
female to show details of mastology.
Note the five pairs of mammae char-
acteristic of weasels, and the uneven
arrangement of mammae of the two
sides which is also common among
weasels.

MUSTELA ERMINEA

95

1 B+M M.e.orctico

2 ^SM M.e.poloris

3 ^H M.e. sempici

4 I I M.e.kodlacensis

5 llllllll M.e.richardsonii

6 ^S M.e.cicoqnanii

7 l'-'--Vv-v1 M.e.banqsi

8
9

10
I I
12
13

M.e.invicta

M.e.alascensis

M.e.salva

M.e.initis

M.e.celendo

M.e. seclusa

4

15!

I6l

17

18

19

20

M.e.haidarum
1 M.e.anquinoe
I M.e.fallenda
J M.e. olympico
M.e. strcatori
M.e. quiosa
M.e. muricus

Fig. 25. Map showing geographic ranges of the subspecies of Mustela

erminea in the New World.

For rearing their young, ermines live in burrows. Bishop ( 1923),
in Albany, New York, found a burrow occupied by four young and
a pair of adults. The burrow had many galleries and contained
a nest constructed of rat fur, fine grass and fragments of leaves.

96 University of Kansas Publs., Mus. Nat. Hist.

At Woods Lake, Fresno County, California, in early August, Ingles
observed (1942) some young and at least one adult at their den
which was in a burrow beneath a hollow tree. The ermines used
the hollow root and the hollow tree as well as the burrow beneath.
Seton (1929 (2):591) quotes S. Eldon Percival, of Barretts Rapids,
Ontario, as finding the living quarters of an ermine in unthreshed
grain stacked in a barn and says (op. cit. :590) that John Burroughs
dug out a nest, composed of leaves and the fur of mice and moles,
two or three handfuls in bulk, from a cavity the size of a hat, arched
over with a fine network of tree roots.

Four instances in which the male as well as the female was
present at a den containing young are cited by Hamilton ( 1933:328)
and he gives some evidence, although not at all conclusive, that
"adults customarily pair, or at least run together, at times other
than the breeding season". No other writers remark on this matter.
I doubt that adult ermines are associated in pairs for most of the
year but such may be the case.

Mustela erminea arctica ( Merriam )

Ermine

Plates 2, 3, 4, 9, 10, 11 and 41

Ptitorius arcticus Merriam, N. Amer. Fauna, 11:15, pi. 2, figs. 1, la, and pi.

5, figs. 6, 6a, June 30, 1896.
Putorius (Gale) erminea, Coues, Fur-bearing animals, p. 109, 1877 (part).
Ptitorius richardsonii. Bangs, Proc. Biol. Soc. Washington, 10:16, pi. 1, figs.

3, 3a, pi. 2, figs. 3, 3a, and pi. 3, figs. 6, 6a, February 25, 1896 (part).
Putorius cicognanii alascensis, Osgood, N. Amer. Fauna, 19:43, October 6,

1900.
Putorius kadiacensis, Osgood, N. Amer. Fauna, 21:69, September 26, 1901.
Putorius aiidax Barrett-Hamilton, Ann. and Mag. Nat. Hist., 13(ser. 7):

392, May, 1904, type from Discovery Bay, EUesmere Island.
Putorius alascensis, Heller, Univ. California Publ. Zool., 5:345, March 5,

1910.
Mustela arctica arctica. Miller, U. S. Nat. Mus. Bull., 79:97, December 31,

1912; Dice, Joum. Mamm., 2:22, February 10, 1921.
Mustela arctica. Hall, Univ. California Publ. Zool., 30:420, March 19, 1929.
Mustela erminea arctica, Ognev, The mammals of U.S.S.R. and adjacent

countries, 3:31, 1935; Hall, Proc. California Acad. Sci., 23:559, August

22, 1944; Hall, Joum. Mamm., 26:179, July 19, 1945.

Type.— Male, adult, skull and skin; no. 14062 '23010, U. S. Nat. Mus.;
Point Barrow, Alaska; July 16, 1883; obtained by John Murdock, original no.
1672.

The skull has a fracture, on the dorsal surface, extending from the anterior
nares to the interorbital constriction and another fracture on the left margin
of the nasal bone. The middle of the left zygomatic arch is broken away.
Otherwise the skull is complete. Right incisor one, above and below, are
missing. Otherwise the teeth are present and entire. The skin is in the brown
summer pelage, well made, in a good state of preservation, and shows no ob-
vious signs of fading.

MUSTELA EKMINEA 97

Range. — Arctic regions of Alaska and western Canada from the Pacific
Ocean to Smith Sound; from the northern limit of land south approximately to
a line from Skagway through Ft. Goodhope, north shore of Great Bear Lake,
south shore of Clinton Golden Lake, north shore of Baker Lake, west end of
Wagner Bay to south end of Committee Bay. See figure 25 on page 95.

Characters for ready recognition. — Differs from M. e. polaris in darker upper
parts (Raw Umber rather than Buckthorn Brown) and less intensely colored
underparts that are Sulphur Yellow, Colonial Buff or Primrose Yellow rather
than Buff Yellow; from M. e. semplei, in males, in that hind foot more than 44
and basilar length more than 41 and in that females average larger, the skulls
of females being only about 11 per cent heavier; from M. e. kadiacensis in
hind foot more than 33 in females, zygomatic breadth amounting to more,
rather than less, than distance between last upper molar and jugular foramen
irrespective of sex; from M. e. richardsonii, alascensis, salva and initis, both
sexes so far as known, by proximal two-thirds of under side of tail colored
same as underparts rather than same as upper parts, and by zygomatic breadth
amounting to more, rather than less, than distance between last upper molar
and jugular foramen.

Description. — Size. — Male: Six adults from Tanana, Alaska, yield average
and extreme measurements as follows: Total length, 336 (310-350); length
of tail, 93 (84-105); length of hind foot, 49 (45-51).

Female: Five adults, one each from Alatna River, mountains near Eagle,
Kamarkak in Alaska, Arctic Red River and Baillie Island in Canada, yield
average and extreme measiurements as follows: Total length, 285 (272-304);
length of tail, 77 (68-95); length of hind foot, 39 (34-43).

Weight of 5 subadult males from Tanana is 206 (163-248) grams; adults
would be heavier.

Color. — Winter pelage all white except tip of tail. Summer pelage with
upper parts uniform in color and Raw Umber or darker (16n) of Ridgway
and about tones 2 to 3 of Chocolate of Oberthiir and Dauthenay, pi. 343, but
in autumn some specimens have more light red than tones 2 or 3. Underparts
Sulphur Yellow, Colonial Buff, or Primrose Yellow, often white on chin and
insides of forelegs; color of underparts extends narrowly over upper lips, distally
on posterior sides of forelegs onto antipabnar surface of forefeet, onto proximal
two-thirds or three-fourths of underside of tail as length of tail is measured
along tail-vertebrae, on medial sides of hind legs to a point between knee and
ankle but reappears on antiplantar faces of toes and in some individuals is
narrowly continuous onto toes; rim of ear in some specimens with short, white
or pale hairs giving ears distinct whitish border; least width of color of under-
parts averaging, in adult males from Alaska, 65 (46-93) per cent of greatest
width of color of upper parts. Black tip of tail in 5 males in winter pelage
from Tanana averaging 84 (70-93) mm. which is 91 (75-107) per cent of
length of tail-vertebrae.

Skull. — Male (based on 5 adult topotypes): See measurements and plates
2-4. As described in Mustela erminea richardsonii except that: Weight, 3.5
(3.1-3.9) grams; basilar length 42.5 (41.8-43.3); length of tooth-rows more
than length of tympanic bulla; breadth of rostrum measured across lacrimal
processes averaging more than a third of basilar length; interorbital breadth

4—3758

98 University of Kansas Publs., Mus. Nat. Hist.

more than distance between glenoid fossa and posterior border of external
auditory meatus; zygomatic breadth more than distance between last upper
molar and jugular foramen.

Female (based on 2 adult topotypes and 2 adults and 4 subadults from
central Alaska): See measurements and plates 9-11. As described in Mustela
erminea richardsonii except that: Weight, 1.5 (1.2-2.0) grams; basilar length,
35.7 (34.5-37.0); length of tooth-rows more than length of tympanic bulla;
breadth of rostrum more than 30 per cent of basilar length; interorbital breadth
more than distance between glenoid fossa and posterior border of external
auditory meatus; zygomatic breadth more than distance between last upper
molar and jugular foramen (except in specimens from Ellesmere Island where
two distances are approximately equal).

Cranial differences from Mustela erminea kaneii (which occurs
on the Asiatic side of Bering Strait), in both males and females,
are: larger size relatively as well as actually, broader except in
mastoidal region where relatively (to basilar length) the width is
less; preorbital part of skull broader as well as longer.

From kadiacensis differences in the skull of the male are: size
less; 13 per cent heavier, relatively (to basilar length) narrower
across interorbital region and zygomatic arches; tympanic bullae
relatively as well as actually narrower. Judging by the single avail-
able adult female of kadiacensis, the skull of female arctica is larger
in all parts measured, a fourth heavier, has tympanic bullae of al-
most twice the volume and the interorbital and preorbital regions,
relative to the braincase, are much reduced in whatever plane
measured.

Differences from richardsonii, additional to those noted above in
the formal description of the skull, between the males, are: larger
in all parts measured except length of tympanic bulla which is about
the same; 42 per cent heavier; relative to basilar length, skull broader
with preorbital part longer as well as broader; tympanic bullae more
inflated posteriorly. The same differences prevail between females
except that the skull is 36 per cent heavier and in arctica the length
of the bulla is actually more ( although relative to the basilar length
less ) and its greater inflation posteriorly is hardly perceptible. Dif-
ferences from alascensis, additional to those indicated in the formal
descriptions of the skulls of the two, in males, are: larger in every
part measured; 95 per cent heavier; relative to the basilar length,
skull broader with preorbital part longer as well as broader; meas-
ured at a point opposite the foramen lacerum anterius, the width of
the pterygoid space is more, rather than less, than 40 per cent of
its length. Excepting this difference in width of interpterygoid
space, the same differences prevail between females, those of arctica
being 56 per cent heavier.

MUSTELA ERMINEA 99

Comparison with semplei is made in the account of that sub-
species.

Skull indistinguishable from that of polaris.

Remarks. — The person who studies specimens of this subspecies
finds labels inscribed with the names of naturalists well known to
all readers of literature on the Arctic. Sir John Franklin, R. Mc-
Farlane, R. Kennicott, E. W. Nelson and R. M. Anderson are names
which appear commonly. Of Alaskan specimens prepared accord-
ing to modern methods, a large share was obtained by O. J. Murie
and L. R. Dice.

The ermine was observed in the far north by early explorers
and was mentioned in the literature, almost always under the name
then used for the ermine of northern Europe and Asia. In 1896
Bangs misapplied to it the name richardsonii but Merriam in the
same year corrected the application of this name and proposed as
new for this weasel the name arctica, the name in use today. For
almost 50 years after Merriam and Bangs wrote about it, arctica
was treated, nominally at least, as a species distinct from its other
relatives in both the Old- and New-World. The subspecific status
of arctica was emphasized in 1944 (555) by the present writer in
reporting in detail upon the specimens, of Mustela erminea, from
Eastern Asia which were made available on loan by Professor B. S.
Vinogradov and the late Anatol I. Argyropulo of the Leningrad
Academy of Sciences. Specimens of Mustela erminea kaneii from
the Asiatic side of Bering Strait and Mustela erminea arctica from
the American side are distinguishable by slight cranial characters
but in coloration and external measurements I can detect no differ-
ences. Merriam's (1896:16) mention of more golden-colored upper
parts and darker underparts in American specimens than in erminea
was the result of his comparison of Alaskan and northern European
specimens. When Old World specimens from eastern Siberia, in-
stead of from Europe, are used the differences mentioned by Mer-
riam do not apply. Incidentally, many Siberian specimens have
the white border, on the ear, which Merriam ( loc. cit. ) noted as a
distinguishing feature of arctica. When Merriam named arctica
he said (1896:15, 16) "Putorius arcticus . . . has heretofore
been confounded with erminea or richardsoni. . . . It is inter-
esting to find in this country an Arctic circumpolar weasel which,
though specifically distinct, is strictly the American representative of
the Old World erminea." Bearing in mind that Merriam's concept of
species and subspecies (see Merriam, 1919:6) differed from that of
nearly all modern systematists it is clear from his statement quoted

100 University of Kansas Publs., Mus. Nat. Hist.

above that he correctly understood the zoological relationship
obtaining between the ermines of the Old and New Worlds.

Ognev (1935:31) seems to have been the first to use the name
combination Mustela erminea arctica for Alaskan specimens.
Thereby he expresses the view adopted here, namely that the
American ermine is subspecifically but not specifically distinct from
the Old World animal. Whether actual intergradation ( crossbreed-
ing ) ever takes place across the narrow Bering Strait I do not know.
I doubt that crossbreeding occurs but considering the Diomedes
(islands), tliat might serve as a half way stopping point, and re-
membering Mr. Charles Brower's oral statement to me that he had
seen tracks of ermine as far as 10 miles from the northern shore of
Alaska out on the ice, the possibility must be granted of an oc-
casional individual crossing from one side to the other of Bering
Strait on the ice in winter or of being carried across when the ice
broke up and drifted. If transfers of this kind occurred often one
would expect ermines to occur also on Saint Lawrence Island where
apparently they do not. The one skin (U. S. Nat. Mus. no. 259046)
seen as labeled from there, my friend, Otto William Geist ascer-
tained was imported as a skin with other furs from Siberia.

Ognev (op. cit.) who used the name combination Mustela er-
minea arctica for Alaskan specimens, applied it also to animals from
Kamchatka. At the same time he recognized the animal from the
eastern mainland of Siberia (as opposed to the peninsula of Kam-
chatka) under the name Mustela erminea orientalis Ognev 1928.
Hall (1944:556) applied the earlier proposed name Putorius kaneii
Baird 1857, to the animal on the eastern mainland of Asia and pro-
posed the new name Mustela erminea digna for the ermine of Kam-
chatka. In comparing material of these two Asiatic races with topo-
types and other specimens of M. e. arctica from Alaska, it seemed to
me that the degree of relationship, one with the other, was about the
same. M. e. digna has a slightly larger preorbital region than M. e.
kaneii, and the skull is longer. In both of these particulars digna
approaches closer to arctica. M. e. kaneii has longer tympanic
bullae and a wider skull than digna and tlierein approaches more
towards arctica than toward digna. As nearly as I can make out,
digna and kaneii show a nearly equal degree of resemblance to
arctica. Also the degree of difference between digna and kaneii is
about the same as between either one of them and arctica. In view
of the above considerations the ermines of the New and Old worlds
are here regarded as only subspecifically distinct.

In the original description of Putorius audax (here regarded as

MUSTELA ERMINEA 101

inseparable from Ptitorius arcticus Merriam) Barrett-Hamilton er-
roneously designated the type locality as "Discovery Bay, North
Greenland" whereas he should have written Grinnell Land [= El-
lesmere Island of modern terminology] in place of Greenland.
As reference to Nares ( 1877 and 1878 ) will readily reveal, Discovery
Bay is near 65° W and 81° 40' N, across Robeson Channel, to the
west, from Greenland. The label on the type specimen and the
specimen register in the British Museum of Natural History each
designates the locality for this specimen, the type of audax, as
Discovery Bay without mention of Greenland. The published
accounts of Feilden (1878) and Nares (1877 and 1878) state that
specimens of ermine were obtained at Discovery Bay. Probably
H. C. Hart is the collector of the specimen; he was the naturalist
attached to H, M. S. Discovery which wintered at Discovery Bay
while H, W. Feilden was the naturalist attached to H. M. S. Alert
which wintered a few miles southeast of Cape Sheridan, also on
the eastern coast of Ellesmere Island.

It is true that from these ships a trip was made into Greenland
and an ermine (only one individual it seems) was obtained tliere,
but this individual was the type specimen of Mtistela erminea
polaris, in the account of which race something of the history of this
specimen is given.

With the material available — and it is not entirely adequate — I
can detect no features by which animals from the type locality of
audax can be distinguished from typical arctica which latter name
has priority.

Intergradation with richardsonii probably occurs completely
across the continent. Intergrades here referred to arctica include
those from Fort Goodhope. The one defective specimen from Lake
Lebarge, Yukon, is not certainly identified as arctica and how far
west of Teslin Lake tlie boundary-line between arctica and richard-
sonii should be drawn remains to be ascertained. The one specimen
available from Hinchenbrook Island, no. 912 Mus. Vert. ZooL, an
adult female, is doubtfully referred to arctica because the damaged
tympanic bullae appear to be no larger than in alascensis, and the
size of the skull is more as in alascensis although intermediate be-
tween that race and arctica. Shape of the skull is more as in arctica.
Possibly more nearly adequate material would show the existence
on Hinchenbrook Island of an insular race differing in about the
same degree from arctica of the mainland as does the insular
kadiacensis. Nevertheless, the males from farther south at Cape
Yakataga are in all respects arctica and this argues against near

102 University of Kansas Publs., Mus. Nat. Hist.

relationship to alascensis of the animal on Hinchenbrook Island.
The three animals seen from Yakutat Bay are so young as not to
display clearly the cranial characters of the subspecies but the
extension of the color of the underparts onto the underside of the
tail in them and also in the skin without corresponding skull from
Glacier Bay, Alaska, is as in arctica, the race to which they are
referred, and gives substantial basis for showing the geographic
range of arctica as extending this far south along the Pacific Coast.
Specimens examined. — Total number, 281, arranged alphabetically by Dis-
tricts and from north to south in each District. Unless otherwise indicated,
specimens are in the collection of the United States National Museum.

Alaska. Point Barrow, 22 {V, l^ 4', 7\ 6°); Flaxman Island, 3; Collinson
Point, 1^ Sahrochet River, 1^ Hulahula River, 1^ 69°20' & 141°, 1; Rampart
House, 1; Yukon River, mouth of Porcupine River, 18; Alatna River, 30 mi.
from mouth, 1; Koyakuk Riv., 16 mi. below Bettles, 4; Shelton, 1'; Kruzamepa,
1'; Tanana, 6; Boulder Creek, Chena River, 3; Fort Reliance, 4; Yukon River,
20 miles above Circle, 2; Mts. near Eagle, 42 (1*); Snake River, Nome, 1';
Nulato, 3; No(e)wikakat Riv., 1; Kantishna, 3; Fairbanks, 5 ( 1 20 mi. E and
1 33 mi. E); Richardson, 1; N. Fk. Kuskokwim R. at base of Mt. Sischo, 1;
N. Fk. Kuskokwim R. at Junction with McKinley Fk., 1; Nenana Riv., mouth
of Maurice Cr., 1; Ober Cr., trib. of Jarvis Cr., Delta Riv. region, 1; head of
Savage Riv., near Jennie Cr., 1; Wonder Lake, 1°; Bear Cr., 3; Unlakleet, 3;
St. Michaels, 11; 125 mi. E and a little N of Knik, Cook Inlet, on S side
Matanuska Range, 1*; Hope, Cook Inlet, 1; lak Lake, 1*; head of Behring Riv.,
1; Bethel, 2; Kenai Lake, 8; Kenai Peninsula, 13 (2'); He[i]nchenbrook Island,
1200 ft., T; Sunshine Point, KaUekh River, Yakataga Dist., 1"; Cape Yakataga,
3"; Yakutat Bay, 3°; Seward, 7; Seldovia, 22 (4'); Homer, 1^ Cape Elizabeth,
18; Akchookuk Lake, 1; Lake Weelooluk, 1; Kokwok Riv., 80 mi. up, 4;
Nushagak, 1; Nushagak Riv., 1; Kolukuk, 1; Egooshik River at mouth, 1;
Glacier Bay, 1; Becharof Lake, between Portage Bay and Becharof Lake, 1;
Ugashik Riv., 4; Chignik, 7; East base Frosty Peak, 1; Pavlov Bay, 1°; Mt.
Pavlof, 1"; Unimak Island, 2 (1^).

District of Franklin. Cape Sheridan, 1'; Discovery Bay, Ellesmere Island,
1" (type specimen of Putorius audax Barrett-Hamilton); Axel Heiberg Island,
1"; Bache Peninsula, Ellesmere Island, 1°; Bedford Pims Island, 4'; Craig Har-
bor, 2"; Cape Kellett, Banks Island, 1'; Franklin Isthmus, 1"; King William
Island, 2".

District of Keewatin. Ualiak, Ogden Bay, 2".

District of Mackenzie. Baillie Island, 1"; FrankUn Bay, 1; Langton Bay, arm
of Frankhn Bay, 15 mi. S of, 1'; Cockbum Point, 69°N, 115°W, 2"; Dolphin
and Union Strait, 1°; Bernard Harbor, 2°; Kent Peninsula, 4'°; Horton Riv.,
near Fort Anderson, 1; Fort Anderson, 6; Anderson River, 3; Barry Island,
Bathurst Inlet, V; Fort McPherson, 1; Peels River, 2; Arctic Red River, 8=;
Fort Good Hope, 6; Clinton Golden, F.

Yukon. Kamarkak, 1"; Herschel Island, T; Lapierres House, 2; Forty Mile,
L. T. Coal Cr., 4°; head of Coal Cr., 1; Macmillan River, Forks, 1; 20 mi. W.
Ft. Selkirk, 1; Slims River, near Kluane, 1'; head of Lake Lebarge, 1.

1. American Mus. of Nat. History 7. Carnegie Museum

2. Museum of Comparative Zoology 8. Leland Stanford Junior University

3. Acad. Nat. Sciences of Philadelphia 9. University of Oklahoma.

4. Field Museum of Natural History 10. Univ. Zool. Mus., Copenhagen

5. Mus. Vert. Zocil., Univ. California 11. British Museum of Natural History

6. Canadian National Museum 12. California Academy of Sciences

MUSTELA ERMINEA 103

Mustela erminea polaris (Barrett-Hamilton)
Ermine

Putorius orcticus polaris Barrett-Hamilton, Ann. and Mag. Nat. Hist., 13

(ser. 7):393, May, 1904.
Mustela erminea, Manniche, Meddelelser om Gr0nland, 45:80-85, 1 fig.,

1910.
Mustela arctica polaris, Miller, U. S. Nat. Mus. Bull., 79:97, December 31,

1912.
Mustela erminea polaris. Hall, Joum. Mamm., 26:179, July 19, 1945.

Type. — Probably female, skin only; no. 78. 6. 19. 11, Brit. Mus. Nat. Hist.;
Gap Valley, Di miles northeast Cape Brevoort, 82° N, 59° 20' W, Northwestern
Greenland; June 15 or 16, 1876; obtained by Lewis A. Beaumont.

The skin is in full, fresh summer pelage, fairly well stuffed except for the
tail which is unstuffed; the whole is in a good state of preservation.

Range. — North coast, and east coast as far south as Turner Sound (between
69 and 70 degrees) of Greenland. See figure 25 on page 95.

Characters for ready recognition. — Differs from M. e. arctica in lighter upper
parts (near[/] Buckthorn Brown rather than Raw Umber or darker) and more
intensely-colored underparts that are Buff Yellow rather than Sulphur Yellow,
Colonial Buff, or Primrose Yellow; from M. e. semplei in color in same fashion
as from arctica and in larger size of skull.

Description. — Size. — Male: One subadult and two adults (one ad. from
Sc0resby Sound and other two from Ymer Island) measure as follows, the
average being given first: Total length, 318 (301, 320, 315); length of tail,
72 (69, 70, 73); length of hind foot, 46.5 (44, 46, 47).

Female: No measurements taken in the flesh available but hind foot,
measuring 33.5 in the dried state and therefore approximately 35 in hfe.

Color. — As described in Mustela erminea arctica except that upper parts
in summer near(/) Buckthorn Brown and tone 4 of Dark Fawn of plate 307
to tone 1 of Raw Umber of plate 301 of Oberthiir and Dauthenay. Underparts
Buff- Yellow. Least width of color of underparts averaging, in 3 males, 66
(57-72) per cent of greatest width of color of upper parts. Black tip of tail
in same males averaging 71 (70-72) mm. which is 99 (99-104) per cent of
length of tail-vertebrae.

The fighter-colored upper parts and more intensely yellow underparts are the
distinguishing features of the subspecies polaris in comparison with other races
of American M. erminea.

Skull. — Male (based on 5 adults from eastern Greenland): See measure-
ments. As described in Mustela erminea richardsonii except that: Weight
more (not recorded); basilar length, 41.3 (39.0-42.4); length of tooth-rows
more than length of tympanic bulla; breadth of rostrum measured across
lacrimal processes averaging more than a third of basilar length; interorbital
breadth more than distance between glenoid fossa and posterior border of
external auditory meatus; zygomatic breadth more than distance between last
upper molar and jugular foramen.

Female (based on 2 adults. Turner Sund and Kap Hoeg): See measure-
ments. As described in Mustela erminea arctica except that basilar length
36.8 (35.9, 37.8), and length of tooth-rows not more tlian length of tympanic

104 University of Kansas Publs., Mus. Nat. Hist,

bulla. Skulls of females not in hand when this comparison is written; only the
recorded measurements are available.

To me the skull of polaris is indistinguishable from that of arctica.
Therefore the comparisons made of the skull of arctica with those of
other subspecies will apply also for polaris.

RemarJcs. — In view of the heretofore erroneous assignment of the
type locality of Mustela erminea audax to Greenland, pains were
taken to verify the statement by Barrett-Hamilton (1904:393) rela-
tive to the type specimen of polaris. Taking pains thus seemed the
more worthwhile because in the specimen register at the British
Museum of Natural History, there is written to the right of cata-
logue numbers 78 - 6 = 19 nos. 1 - 11, "Discovery Bay Presented by
Mr. Hart Arctic Collection." This refers to no. 78.6.19.1. There
are no ditto marks below but by implication this data applies also
to nos. 1-11, which include the holotype of polaris. A label at-
tached to the specimen does however give the locality as "Hall
Land" "N Greenland" and another label has on it "Ermine, pro-
cured by Mr. Beaumont Greenland Lat 89° Long W 59-20." The
89° is obviously a mistake ( on the label or in my transcription of it )
for 82°.

Reference to Nares (1877:385) reveals that Lieutenant Lewis
A. Beaumont, under date of June 15 and 16, 1876, wrote in his field
journal as follows: "I shot an ermine." In the daily accounts of his
journey from Discovery Bay on Grinnell Land [^ Ellesmere Is-
land], across Robeson Channel and along the north coast of Green-
land to the west base of Mount Farragut near 50° 30' W he men-
tions the ermine only this once. For several other kinds of animals,
Beaumont mentions individuals seen or shot, often with the nota-
tion that this is the second, or third seen. This mention of a kind
of animal whenever seen was in accordance with orders. On page
39 of the Discovery Report {op. cit., 1877) in "General orders to
sledging parties" by Captain G. S. Nares, Commanding the Expedi-
tion, we find ". . . note daily: IV State the animals seen and
those shot." Reference to the map facing page 358 of the ( op. cit. )
report reveals that on the 15th and 16th, camps were made by
Beaumont in Gap Valley, each 7% miles northeast of Cape Brevoort,
one camp on either side of the 82° line, and separated from each
other by a distance of only 2/4 air hue miles or 4/2 miles march ac-
cording to his journal.

These several data, then, are the bases for designating the type
locality of M. e. polaris, in the way that I have stated it at the begin-
ning of this account of the subspecies.

MUSTELA ERMINEA 105

The light-colored upper parts and more intensely yellow iinder-
parts well differentiate this subspecies from arctica or scmplei.
Intergradation is suggested by a skin, no. 1462, Copenhagen Zoo-
logical Museum, from Axel Heibergs Land, the color of the under-
parts of which agrees with that of specimens from Greenland. Also
the color of the upper parts is decidedly nearer that of animals from
Greenland than to that of specimens from Ponds Inlet, Tulican ar.d
Gifford River. No other specimens west or south of Greenland
suggest intergradation. In Greenland itself, one adult, a female
from Turner Sund, East Greenland, has the underparts no more
yellowish than in some specimens from Melville Peninsula. This
female is darker on the back than any one of the other 10 specimens
from Greenland in summer pelage examined at the same time, but
even so is not so dark colored as animals from Baffinland or other
islands to the west of Greenland.

The final summation of information about this subspecies would
have been more precise if I had been able to have actually in hand,
at the time of writing, specimens preserved in the Copenhagen
Zoological Museum. The war made it impractical to secure the
loan of these as previously planned. Even so, the measurements
and notes on color that I obtained from this material, in 1937, in
Copenhagen, suffice to prove that the subspecies polaris is well set
off in color from the other American subspecies of Mtistela erminea.

The best material of this subspecies is in the University Zoo-
logical Museum at Copenhagen, Denmark.

Specimens examined. — Total number, 35, arranged by locality from the
western end of the north coast of Greenland, eastward and then southward
down the east coast. Unless otherwise indicated, specimens are in the Uni-
versitetets Zoologisk Museum, K0bnhavn, Danmark.

Gap Valley, 7% mi. NE Cape Brevoort, 82 N, 59 20' W, 1 ( British Mus. ) ;
Dragon Point, 1; Danmarks Havn (Fjeldene ved Baadskjeret, 1; hlle Fjeld, 1;
Lyservig, 1; harefjeldets, 4; Rypefjeldet, 1; Baadskjeret, 1; Danmarkshavn, 3)
12; Christians Havn, 1 (not found on map); Shannon Island, 4; Germania
Havn, 2; Claveringoen, 1; Carls Havn, 1; Myggbukta, 2 (British Mus.);
Ymer[s] Island, 2 (Mus. Comp. Zool. ); Kap Hoegh, lamesonsland, 1 (Berhn
Zool. Mus.); Scoresby Sund, 3; Turner Sund, 4.

Mustela erminea semplei Sutton and Hamilton

Ermine

Plates 2, 3, 4, 9, 10 and 11

Mustela arctica semplei Sutton and Hamilton, Ann. Carnegie Mus., 21:79,

February 13, 1932.
Mustela arctica labiata Degerbol, Kept. 5th Thule Exped., 2 (no. 4):25,

1935, type from Malugsitaq, Melville Peninsula, Canada.
Mustela erminea semplei. Hall, Journ. Mamm., 26:179, luly 19, 1945.

Type. — Male, subadult, skull and skin; no. 6470, Carnegie Mus.; Coral Inlet,

106 University of Kansas Publs., Mus. Nat. Hist.

South Bay, Southampton Island, Canada; October 8, 1929; obtained by George
Miksch Sutton, original no. 3M.

The skull has two holes in it: one is immediately above the left canine,
and the other ( 2 X 5.5 mm. ) is 3 millimeters to the left of the median line at
the juncture of the frontal and parietal bones. From this last mentioned hole
a fracture extends back halfway to the lambdoidal crest. The tip of the left
upper canine is broken oflF. Otherwise the skull is complete, and the teeth
all are present and entire. The skin is well made and in fresh white winter
pelage except for a trace of the old brown summer pelage on the back, on the
tail, on the anterior borders of the ears, and in a spot 11 mm. long and 8 mm.
wide on the nose.

Range. — Baffin and Southampton islands, Melville Peninsula and west side
of Hudsons Bay as far south as Eskimo Point. See figure 25 on page 95.

Characters for ready recognition. — DifFers from A/, e. arctica, in that, in
males, hind foot less than 44 and basilar length less than 41 and in that
females average smaller, their skulls being only about 10 per cent lighter; from
M. e. polaris in darker upper parts ( Raw Umber rather than Buckthorn Brown )
and less-intensely-colored underparts that are Sulphur Yellow, Colonial Buff or
Primose Yellow rather than Buff Yellow, and in lesser size in the same fashion
as from arctica; from M. e. richardsonii, of both sexes, in that proximal two-
thirds of under side of tail colored same as underparts rather than same as
upper parts and by least interorbital breadth amounting to more, instead of less,
than distance between glenoid fossa and posterior border of external auditory
meatus.

Description. — Size. — Male: Ten adults and subadults, from Southampton
Island, yield average and extreme measurements as follows: Total length, 282
(267-318); length of tail, 77 (59-87); length of hind foot, 40 (38-43).

Female: Four subadults from Southampton Island yield average and ex-
treme measurements as follows: Total length, 271 (256-288); length of tail,
71 (69-74); length of hind foot, 35 (33-38).

Color. — As described in M. e. arctica except that least width of color of
underparts averaging, in 7 males, 59 (45-81) per cent of greatest width of color
of upper parts. Black tip of tail in 19 male topotypes averaging 72 ( 64-83) mm.
which is 91 (75-122) per cent of length of tail-vertebrae.

Skull. — Male (based on 2 adults and 10 subadults from Southampton Is-
land ) : See measurements and plates 2-4. As described in Mustela erminea
richardsonii except that: Weight, 2.0 (in one subadult) grams; basilar length,
37.5 (35.7-39.9); length of tooth-rows more than length of tympanic bulla;
breadth of rostrum more than a third of basilar length; interorbital breadth
more than distance between glenoid fossa and posterior border of external
auditory meatus; zygomatic breadth more than distance between last upper
molar and jugular foramen.

Female (based on 1 adult and 4 subadults from Southampton Island): See
measurements and plates 9-11. As described in Mustela erminea richardsonii
except that: Weight, 1.35 (in one adult) grams; basilar length, 34.2; breadth
of rostrum more than 30 per cent of basilar length; interorbital breadth more
than distance between glenoid fossa and posterior border of external auditory
meatus; zygomatic breath more or less than (approximately same as) distance
between last upper molar and jugular foramen.

MUSTELA ERMINEA 107

In comparison with richardsonii, the skulls of males averaged
smaller in every measurement taken except breadth of rostrum and
interorbital breadth which are more, and zygomatic breadth and
length of inner lobe of Ml which are approximately the same; skull
about 20 per cent lighter; in relation to basilar length, preorbital
region longer and broader in every part measured. Female aver-
ages larger, in every part measured; 23 per cent heavier; in relation
to basilar length, every other measurement more. It is noteworthy
that the skull of the male is smaller and the skull of the female larger
than in richardsonii.

Differences from arctica are: Size less, in each sex; males about
40 per cent and females 10 per cent lighter; in males, skull more
rounded in outline as viewed from above because zygomatic arches
arise less abruptly from skull; in males tympanic bullae do not
project so far ventrally from squamosal floor of braincase; with
these exceptions, skull of semplei can be said to be a smaller edition
of that of arctica.

From polaris, semplei difFers, cranially, in the same way as from
arctica.

Remarks. — There is a slight increase in size of ermines toward the
north which probably is the result of intergradation between semplei
and arctica. Specimens from the northern part of Baffin Island are
larger than those from farther south. Specimens from the main-
land west of Southampton Island may owe their smaller (than in
arctica) size to intergradation with richardsonii almost as much as
to intergradation with semplei.

Degerbc^l's name Mustela arctica lahiata was applied to speci-
mens, which to me are indistinguishable from topotypes of Mustela
arctica semplei, which latter name has three years priority. Deger-
b</)l (1935:34) states that Malugsitaq, Melville Peninsula, is the type
locality. He did not designate a type specimen. Reference to his
account (op. cit.:2Q) shows that he lists five specimens from the
type locality, or more precisely as "Malugsitaq, Lyon Inlet. 5 sum-
mer skins, s $ June-July 1922. P. F., CN. 2262—2266." On
labels attached to these specimens, "Lyon Inlet" is replaced with
"Melville Peninsula." On July 28, 1937, Degerb(/)1 and I together
examined these specimens in his laboratory. Because no. 2262 is
first mentioned I regard it as the type. It is a juvenal male, skull
and skin, no. 2262 (20.5 1931.8), Univ. Zool. Mus. Copenhagen,
obtained in June or July of 1922 by Peter Freuchen whose original
number was / s 2324. The specimen is one of 5 males taken at the
same locality by the same collector and they bear identical data as

108 University of Kansas Publs., Mus. Nat. Hist.

to date. They look to be of the same litter for all are roughly of the
same size and each retains milk teeth.

Additional females, with external measurements carefully taken,
are much needed from Southampton Island, because the available
females are insufficient to show the degree of sexual dimorphism.
If the meager data available be accepted, the difference in size
between the two sexes is less than in other subspecies. My own
feeling is that a better sample of females would show the secondary
sexual difference in size to be more than available data indicate.

Specimens examined. — Total number, 183, arranged from north to south
by islands, or regions attached to the mainland, and from north to south in
each region or island. Unless otherwise indicated, specimens are in the
Zoological Museum, University of Copenhagen, Denmark.

Baffin Island. Pond(s) Inlet, 8; (5'); Tulukan (sometimes spelled Tulu-
kat), 6; Cape Eghnton, 1'; Gifford River, 2; Clyde, 3'; head of Cumberland
Sound, 1*; Pangnirtung, 2'; Kingnait Fiord, V; Kikkulin Island, Cumberland
Sound, 1"; Blacklead Island, Cumberland Gulf, 1; merely Cumberland Gulf,
1'; merely east BafBnland, 34'; Cape Dorset, 2°; SW coast of Baffinland, V.

Melville Peninsula. Iglulik, 3; Pingerqalik, 2; Kingadjuaq, Amitsog, 3; Rae
Isthmus, 3; Lyons Inlet, 13(9°); M[N?] alugsitaq, Lyon Inlet, 5; Itibdjeriang, 2;
Repulse Bay, 27 (22', 2'); Drichetts Cove, Hurd Channel, V; Gore Bay, 1;
Haviland Bay, 1; Cleveland Harbor, Frozen Strait, 1.

Southampton Island and adjacent islands. Danish Island, 11; Vansittart Is-
land, 4. Southampton Island: Coral Inlet, 19 (1', 18'); Prairie Point,
1'; I^Iunnimunnek Point, South Bay, 5'; Native Point, 1^; Ranger Rim, 1';
Koodloatok (not found on map), 1'; merely Southampton Island, 1'; Gore Bay,
1°; Fox Channel, 2'.

Mainland to west of Southampton Island. Cape FuUerton, 3 (1', 2°); Ches-
terfield Inlet, 4 (1', 1'); Tavane, 1'; N of Wagner Inlet, 1; Eskimo Point, 1'.

Mustela erminea kadiacensis (Merriam)

Ermine

Plates 2, 3, 4, 9, 10 and 11

[Putorius arcticus] subspecies kadiacensis Merriam, N. Amer. Fauna, 11:16,

June 30, 1896.
Putorius kadiacensis, Preble, Proc. Biol. Soc. Washington, 12:169, August

10, 1898.
Mustela kadiacensis, Miller, U. S. Nat. Mus. Bull., 79:97, December 31,

1912.
Mustela erminea kadiacensis, Hall, Journ. Mamm., 26:179, July 19, 1945.

Type. — Male, subadult, skull and skin; no. 65290, U. S. Nat. Mus., Biol.
Surv. Coll.; Kodiak Island, Alaska; April 25, 1894; obtained by B. J. Bretherton,
original no. 304.

The skull lacks the basioccipital, part of tlie basiphenoid, the occipital region
on the right side and the posterior part of the right tympanic bulla. The third,
upper, left incisor is missing. Otherwise the teeth all are present and entire.

1. Canadian National Museum 5. American Mus. Nat. History

2. British Museum of Natural History 6. Museum of Comparative Zoology

3. Ro>'al Ontario Museum of Zoology 7. Collection of Edward R. Warren

4. United States National Museum 8. Carnegie Museum

MUSTELA ERMINEA 109

The white, winter skin is only moderately well stufiFed but in a good state
of preservation. The spring coat is appearing along the back. This coat is
visible at only two places unless the hair be parted when the new brown
pelage, which is coming in, can be seen all along the midline of the back.

Range. — Kodiak Island, Alaska. See figure 25 on page 95.

Characters for ready recognition. — Differs from M. e. arctica in hind foot
less than 33 in females and in zygomatic breadth amounting to less, instead of
more, than distance between last upper molar and jugular foramen irrespective
of sex.

Description. — Size. — Male: One adult and 3 subadults yield average and
extreme measurements as follows: Total length, 341 (318-360); length of tail,
93 (86-102); length of hind foot, 47 (44-49).

Female: An adult measures: Total length, 258; length of tail, 70; length of
hind foot, 31.

Color. — As described in M. e. arctica, except that least width of color of
underparts averaging 54 (40-83) per cent of greatest width of color of upper
parts. Black tip of tail in 3 males in summer pelage averaging 80 (70-90)
mm. which is 85 (69-96) per cent of length of tail-vertebrae.

Skull. — Male (based on 2 adults): See measurements and plates 2-4. As
described in Mustela erminea richardsonii except that: Weight 3.1 grams;
basilar length, 42.6 (42.1-43.2); length of tooth-rows more than length of
tympanic bulla; breadth of rostrum measured across lacrimal processes aver-
aging more than a third of basilar length; interorbital breadth more than dis-
tance between glenoid fossa and posterior border of external auditory meatus.

Female (based on one adult, no. 98042) : See measurements and plates 9-11.
As described in Mustela erminea richardsonii except that: Weight, 1.2 grams;
basilar lengdi, 33.0; length of tooth-rows more than length of tympanic bulla.

Comparison with arctica has been made in the account of that
subspecies. Although richardsonii and kadiacensis are described as
having the zygomatic breadth less than the distance between the
last upper molar and jugular foramen, the zygomatic breadth is con-
siderably more in kadiacensis than in richardsonii; consequently the
two dimensions are more nearly equal than in richardsonii. Except
for being slightly narrower, the skull of kadiacensis is only a slightly
smaller edition of that of arctica.

Remarks. — When naming the weasel from the mainland of Alaska
as new, under the name Pittorius arcticus, Merriam ( 1896:16) wrote:
"A small form of arcticus occurs on Kadiak Island. . . , It is
probably worthy of recognition as subspecies kadiacensis." The in-
formality of this description possibly was in part due to the de-
scriber's recognition of the fact that the degree of difference be-
tween arcticus and the insular kadiacensis was slight. Specimens
collected after Merriam proposed the name for the weasel of Kodiak
Island show the animal there to be less different from arctica of the
adjacent mainland than he thought; small size is the most pro-

110 University of Kansas Publs., Mus. Nat. Hist.

nounced distinction of kadiacensis and Merriam's male type speci-
men is smaller than any of the five additional males saved from
Kodiak Island since that time. Even so the differences fully w^ar-
rant subspecific recognition, in my opinion, although kadiacensis is
not a strongly differentiated race. More adult females are needed
to ascertain the norm of form and size for that sex. If the one
female known is typical, the difference from arctica is more pro-
nounced in females than in males. The lesser size of kadiacensis
can hardly be credited entirely to the effect of insularity, for animals
from the southern part of the mainland, on Kenai Peninsula for
example, are smaller than those from central and northern Alaska
and provide evidence of intergradation of a sort between kadiacensis
and arctica.

Specimens examined. — Total number, 9, all from Kodiak Island, Alaska, and
unless otherwise indicated in the U. S. National Museum.

Karluk, 1 (Stanford Univ.); Kodiak, 7; Kodiak Island, 1 (Field Mus. Nat.
Hist.).

Mustela erminea richardsonii Bonaparte

Ermine

Plates 2, 3, 4, 9, 10 and 11

Mustela richardsonii Bonaparte, Charlesworth's Mag. Nat. Hist., 2:38, 1838.

Putorius cicognanii, Baird, Mamm. N. Amer., p. 161, 1858 (part).

Putorius richardsonii, Baird, Mamm. N. Amer., p. 164, 1858 (part-Halifax,

N. S.).
Putorius (Gale) erminea, Coues, Fur-bearing animals, p. 109, 1877 (part).
Putorius richardsoni. Bangs, Proc. Biol. Soc. Washington, 10:16, February

25, 1896.

Putorius cicognani richardsoni, Merriam, N. Amer. Fauna, 11:11, June 30,

1896.
Putorius (Arctogale) cicognanii cicognanii, Bangs, Proc. New England Zobl.

Club, 1:18, February 28, 1899.
Putorius microtis Allen, Bull. Amer. Mus. Nat. Hist., 19:563, October 10,

1903. Type from Shesley, British Columbia.
Putorius arcticus imperii Barrett-Hamilton, Ann. and Mag. Nat. Hist.,

13(ser. 7):392, May, 1904. Type from Fort Simpson, Mackenzie,

Canada.
Putorius cicognanii richardsoni, Preble, N. Amer. Fauna, 27:231, October

26, 1908.

Mustela microtis. Miller, U. S. Nat. Mus. Bull., 79:96, December 31, 1912.

Mustela cicognanii mortigena Bangs, Bull. Mus. Comp. Zool., 54:511, July,
1913. Type from Bay St. George, Newfoundland.

Mustela cicognanii, Sheldon, Joum. Mamm., 13:201, August 9, 1932.

Mustela cicognanii richardsonii, Miller, U. S. Nat. Mus. Bull., 79:95, De-
cember 31, 1912; Hall, Univ. California Publ. Zool, 40:368, November
5, 1934.

Mustela cicognanii cicognanii. Hall, Canadian Field- Nat., 52:108, October,
1938.

Mustela erminea richardsonii. Hall, Journ. Mamm., 26:77, February 27,
1945; Hall, Journ. Mamm., 26:180, July 19, 1945.

Type. — Male, age unknown, skin; no. 43.3.3.4, British Museum of Natural
History; probably from Fort Frankhn, Canada; presented to British Museum
on or before March 3, 1843; may be the type.

MUSTELA ERMINEA 111

In September, 1937, when I searched in the British Museum for the skull,
I found no trace of it nor mention of it in catalogues. The skin is in white,
winter pelage, mounted on a pedestal. See under remarks for Mustela e.
cicognanii for reasons for and reasons against regarding this specimen as the
holotype.

Range. — Hudsonian and Canadian life-zones of the greater part of Canada
from the Atlantic to the Pacific. See figure 25 on page 95.

Characters for ready recognition. — Differs from M. e. arctica, polaris, sem-
plei and haidarum, in both sexes, by proximal two-thirds of under side of tail
colored same as upper parts rather than same as underparts, and interorbital
breadth less, rather than not less, than distance between glenoid fossa and
posterior border of external auditory meatus; from M. e. hangsi, in that, in
both sexes, least width of color of underparts averages two-fifths rather than
about a third of greatest width of color of upper parts, and in that skulls of
males are a fourth heavier, basilar length averaging more than 40; from M. e.
cicognanii, in both sexes, in that least width of color of underparts averages
two-fifths instead of less than a third of greatest width of color of upper parts,
in females by 20 per cent heavier skull (1.1 versus 0.92), in males by skull
more, rather than less, than 1.9 grams, and basilar length more, instead of less,
than 38; from M. e. invicta, in males, by skull more, instead of less, than 1.9
grams; mastoid breadth more, instead of less, than 19.9 mm.; depth of skull at
anterior margin of braincase more, instead of less, than 12.4 mm.; in females, by
same measurement of depth more, instead of less, than 10.1, and weight of
skull averaging more, instead of less, than one gram; from M. e. fallenda in
both sexes upper lips white rather than brown, in males, hind foot more than
41, basilar length more than 38.3, in females hind foot more than 29, basilar
length more than 31.4, and breadth of rostrum amounting to less, instead of
more, than 30 per cent of basilar length; from M. e. alascensis in males in that
black tip of tail more than 43, total length more than 320, tympanic bullae
more than 14 and longer than tooth-row rather than less than 14 mm. and
sometimes shorter than tooth-row, females not individually distinguishable.

Description. — Size. — Male: Four adults (Fort Franklin, Fort Simpson,
Mts. W Fort Nelson, and Govt. Hay Camp, Wood Buffalo Park) yield average
and respective measurements as follows: Total length, 331 average (340, 325,
330, 328); length of tail, 93 (102, 91, 93, 87); length of hind foot, 45 (48, 43,
45, 44). Weight of 4 adults from the Belcher Islands is 175 ( 135-180) grams.
Of 10 subadults from Belcher Islands it is 119 (92-137) grams.

Female: Three adults from Great Slave Lake (Willow River, Fairchild
Point, and Fort Resolution) yield average and respective measurements as
follows: Total length, 252 (237, 238, 282); length of tail, 69 (63, 60, 85);
length of hind foot, 32 (31, 32, 34). Corresponding, average measurements
for three adults from Glacier Lake are 240, 60, 32 and for 3 adults from the
Athabasca Delta, 243, 65, 30. Weight of 8 subadults from the Belcher Is-
lands is 69 (64-78) grams. Weight of adults would be more.

Color. — Winter pelage all white except tip of tail. Summer pelage vidth
upperparts unifonn in color and darker (16n) than Raw Umber, and about
tones 3 to 4 of Chocolate of Oberthiir and Dauthenay, pi. 343. Underparts
Sulphur Yellow, Colonial Buff, or Primrose Yellow, often nearly white on chin
and insides of forelegs; color of underparts extends narrov^ly over upper lips,

112 Unrtersity of Kansas Publs., Mus. Nat. Hist.

distally on posterior sides of forelegs onto antipalmar faces of toes and some-
times over most of antipalmar surfaces of forefeet, on medial sides of hind legs
to a point between knee and ankle but reappears on antiplantar faces of toes
and in some individuals is narrowly continuous onto toes. Least width of color
of underparts averaging, in a series of 12 males from the Athabaska Lake
Region, 40 (25-54) per cent of greatest width of color of upper parts. Black
tip of tail averaging 56 (45-63) mm. in 5 adult males from same region and
thus 60 (48-70) per cent of length of tail-vertebrae.

From arctica, polaris, semplei and kadiacensis, richardsonii differs in: Color
darker; ventral side of tail same color as upper parts; Hght-colored underparts
a fifth narrower; black tip of tail by actual measurement a fifth shorter and
averaging less than two-thirds rather than more than four-fifths of length of
tail-vertebrae. From cicognanii, richardsonii differs in that the underparts are
a fourth wider and in some specimens more brightly colored. The width of
the underparts is likewise a fourth more than in hangsi. In invicta the under-
parts are not so brightly colored as in some specimens of richardsonii. From
fallenda, richardsonii differs in that the upper parts often are lighter colored,
upper lips white rather than colored like upper parts, and underparts as wide
again. In comparison witli alascensis, the black tip of the tail averages three-
fifths rather than a half of length of tail- vertebrae.

Skull. — Male (based on 6 adults from 3 miles south of Big Island, Great
Slave Lake): See measurements and plates 2-4; weight, 2.5 (2.1-2.9) grams;
basilar length, 40.9 (39.6-43.7); length of tooth-rows less than length of tym-
panic bulla; breadth of rostrum measured across lacrimal processes less than a
third of basilar length; interorbital breadth less than distance between glenoid
fossa and posterior border of external auditory meatus; zygomatic breadth less
than distance between last upper molar and jugular foramen.

Female (based on 4 adults: from Willow River, 1; Fort Resolution, 1;
Athabasca Delta, 2; and 2 subadults, one from 3 mi. S Big Island and one
from 15 mi. above Smith Landing): See measurements and plates 9-11; weight,
1.1 (0.9-1.4) grams; basilar length, 33.1 (31.5-34.2); length of tooth-
rows less than length of tv'mpanic bulla; breadth of rostrum less than 30 per
cent of basilar length; interorbital breadth less than distance between glenoid
fossa and posterior border of external auditory meatus; zygomatic breadth less
than distance between last upper molar and jugular foramen.

The skull of the female averages 56 per cent fighter than that of the male.

Comparison of the skull with that of arctica, polaris, semplei,
kadiacensis, haidarum, cicognanii, hangsi, invicta, fallenda, and
alascensis is made in the accounts of those subspecies.

Remarks. — M. e. richardsonii has the most extensive geographic
range of any American race of erminea, is centrally located with re-
spect to the other races, is more abundantly represented by study
specimens in zoological collections than any other race, and is a
sort of average for the species as a whole in most structural features.
Therefore richardsonii is used as a standard of comparison and ac-
cordingly is more fully described than any one of the other races
each of which by reference to richardsonii is described in compara-

MUSTELA ERMINEA 113

tive fashion. This comparative description has the virtue of more
clearly indicating differences between subspecies and also makes
for brevity.

John Richardson, Bernard R. Ross, and names of their com-
panions, as written on the labels of the older specimens recall to the
student's mind early explorations of the north country. Edward A.
Preble obtained important specimens at several places and in recent
years J. Kenneth Doutt and G. G. Goodwin have made the reviser's
work easier by preparing specimens in series from areas not pre-
viously well represented.

The nomenclatural history of this subspecies begins with refer-
ences in the literature that identify the animal as the Old World
species, Miistela erminea — an identification which the study here
reported upon shows to have been correct in the specific, although
not in the subspecific, sense. Richardson, for example, in his
"Fauna Boreah-Americana" published in 1829 so identified the
animal. In 1838, Bonaparte, basing his description on Richardson's
account of 1829, proposed the new name richardsonii. Richardson
himself, the following year in the "Zoology of Beechey's Voyage",
accepted Bonaparte's name and it has been applied to the animal
in the central part of the northern timber-belt of North America
ever since, except as authors used the name Mustela erminea in
the belief that richardsonii was not distinct from erminea.

The north and south boundaries of the range assigned to richard-
sonii varied according to the notions of the particular writer who
was employing the name. Until Merriam in 1896 named arctica as
distinct, animals from the far north were generally included under
the name richardsonii along with populations to which the latter
name now is applied. Because richardsonii grades gradually into
the smaller cicognanii of more southern occurrence the boundary
between the two has been set farther north by one writer and
farther south by another, depending probably upon what the writer
felt was the half-way point in size. This point of course depended
upon the samples selected as typical of richardsonii on the north
and cicognanii on the south. Because Bangs, in 1896, took as rep-
resentative of richardsonii the far northern and hence large-sized
animals ( now separated as M. e. arctica ) , his half-way point in size
between them and the small cicognanii of New England naturally
fell farther north than it would have had he used as representative
of richardsonii specimens from places south of the range of arctica.

In 1903 J. A. Allen proposed the name Putorius microtis for a
specimen from Shesley, northwestern British Columbia, a place ap-

114 University of Kansas Publs., Mus. Nat. Hist.

proximately 50 miles northwest of Telegraph Creek. Considering
the great disparity in size between this one specimen and the other
larger specimens of normal size, from the general region, available
to Allen at that time, it is not surprising tliat he thought two full
species were represented. In 1943 when G. G. Goodwin called to
my attention two males, as small as the type of microtis and taken
by him approximately 300 miles east of Shesley, in the valley be-
tween the Musqwa and Prophet rivers, I for a second time ex-
amined all available specimens and data with the possibility in
mind that microtis was a species or subspecies distinct from M. e.
richardsonii, but again concluded that only one subspecies was in-
volved because no character except size was found to distinguish
the large from the small individuals of a given sex and there are,
preserved from northern British Columbia, individuals of inter-
mediate size. Putorius microtis Allen seems to have been based
on an individual of M. e. richardsonii near the lower limit of size
for that subspecies and microtis is regarded as a synonym.

Barrett-Hamilton in 1904 named the animal at "Fort Simpson,
British Columbia" Putorius arcticus imperii. Preble (1908:232)
pointed out that Fort Simpson on the Mackenzie undoubtedly was
the place intended, and arranged imperii as a synonym of M. e.
richardsonii. The type specimen of imperii was stated to have
been received from B. M. Ross who is known to have collected
specimens, including specimens of this species ( now in U. S. Nat.
Mus.), at Fort Simpson on the Mackenzie. I know of no Fort
Simpson in British Columbia. If, as seems improbable. Port Simp-
son, British Columbia, was the place that Barrett-Hamilton intended
to designate (where so far as I know Ross did not collect), the
name imperii still would seem to be a synonym of richardsonii be-
cause richardsonii seems to be the race of weasel at Port Simpson.
In proposing the name Putorius arcticus imperii, Barrett-Hamilton
stressed that the weasel, which he was naming, was a subspecies
of P. arcticus, gave characters which applied perfectly to richard-
sonii but made no reference to richardsonii. Barrett-Hamilton did
not refer to richardsonii possibly because he relied on Merriam's
classification of 1896 wherein richardsonii is treated as a species dis-
tinct from arctica. Merriam, it will be remembered, held that slight
degree of morphological difference rather than intergradation was
the criterion for subspecies. Although I have no record of having
examined the type specimen of imperii I have but little hesitancy
in treating it as a synonym, and would have no hesitancy at all in
so doing if the type was certainly known to have been obtained at
Fort Simpson on the Mackenzie.

MUSTELA ERMINEA 115

The name Mtistela cicognanii mortigena Bangs, 1913, proposed
for the ermine of Newfoundland, is placed as a synonym of rich-
ardsonii only after repeated, detailed comparisons. In advance of
study I supposed that the isolation of the ermine, in Newfoundland,
had contributed to its differentiation, which, however, the original
describer, Bangs, indicated was slight. Bangs was a careful worker
and I am confident that the differences he described really existed
between his specimens. Material more nearly adequate than he
had from the mainland, shows the males, so far as my measure-
ments and comparisons go, to be in nowise diflFerent from those in
Newfoundland. Females in Newfoundland may have, on the aver-
age, slightly longer hind feet than on the opposite mainland but
I am not certain that they do and even if there is a slight difference
in this regard as suggested by available data, I think it insufficient
basis, alone, for according subspecific status to the insular animal.

The name richardsonii was based by Bonaparte on Richardson's
description which in turn was drawn from a specimen taken at
Fort Franklin, that thus becomes the type locality. It is fortunate
that Preble, in 1903, succeeded in taking specimens there because
the place is near the belt of intergradation between arctica and
richardsonii. Of Preble's two adult males (see Preble, 1908:232)
I have examined no. 133847, which is in transitional pelage and
therefore gives no clue in so far as coloration is concerned, as to
affinities with arctica versus richardsonii. Specimens in the summer
pelage are much to be desired from Fort Franklin. Regardless
of what their coloration may be, specimen no. 133847, in external
measurements and most certainly in cranial features is of the race
to the south and not the race that Merriam named arctica. Because
all specimens from localities to the south of Fort Franklin likewise
differ from arctica of the barren grounds, considerable additional
confidence is felt in allocating the name richardsonii to the animal
which ranges from Fort Franklin southward rather than to the
one, here designated arctica, that occurs to the northward of Fort
Franklin.

Although in most structural features richardsonii is a sort of
average for the American races of the species, it is the extreme in
high degree of sexual dimorphism. The difference in size be-
tween the males and females is greater than in any other race
except possibly M. e. kadiacensis in which so little is known of
the female that the difference between the two sexes cannot be
accurately judged. It will aid in understanding the high degree
of secondary sexual difference in richardsonii to visualize two

116 University of Kansas Publs., Mus. Nat, Hist.

kinds of weasels distributed over the northern half of the continent,
thinking now of the geographic area in America occupied by the
whole species Mustela erminea of which the subspecies richardsonii
is only a part. One of the two kinds of weasel is the male ermine
and the other the female. The decrease in size of the male,
as measured by the weight of the skull, is in the ratio of 7 in the
north to 2 in the south. This decrease is gradual whereas the
corresponding decrease from 3 to 1 in the female is not gradual;
half of the decrease in the female occurs in the short north to
south distance comprised in the belt of intergradation, along
the northern boundary of richardsonii, between it and arctica.
As a result richardsonii is composed of females with medium sized
skulls and males with relatively large skulls, the ratio by weight
being approximately 5 to 2. The disproportion in races of ermines
both to the north and to the south is less. Actually in the north
(arctica) the approximate ratio by weight is 21-^:1; in richardsonii,
2%:1; in the south (muricus), 1%:1. Indicated in still another
way in richardsonii the skull of the female is 56 percent lighter
than that of the male and the skull of the male is 127 percent
heavier than that of the female. Intergradation with races whose
ranges border on that of richardsonii is complete. On the northern
boundary of the range of richardsonii along the western shore of
Hudsons Bay for perhaps a hundred miles north of Eskimo Point,
there are intergrades with arctica. As judged by their lesser size,
individuals of this population are influenced by the sempl ei-stock.
Otherwise, intergradation on the northern boundary, with arctica,
is abrupt whereas intergradation at the south, between richardsonii
and cicognanii, is gradual. Intergradation is similarly gradual
between richardsonii on the one hand and bangsi and invicta on
the other. By speaking of the intergradation as abrupt, it is in-
tended, in this instance, to indicate that in a relatively narrow
belt, between the geographic ranges of arctica and richardsonii,
ermines intermediate in color-pattern, shape of skull, and size,
bridge the gap between the ermine of the tundra (arctica) and
that in the forest belt (richardsonii). It may be added that the
degree of diflFerence between the two subspecies just mentioned
is approximately twice as much as between richardsonii and cicog-
nanii. The intergradation between cicognanii and richardsonii is
gradual. By gradual it is meant that the change from one kind to
the other is achieved in a wider area where ermines from locality
A do not diflFer appreciably from those taken at, say, locality B, 50
miles farther south, although ermines from A and those from a third

MUSTELA ERMINEA 117

locality, C, say, 130 miles south, clearly show differences indicative
of geographic variation.

Specimens examined. — Total number, 1035, as follows. Arranged alpha-
betically by provinces and districts and from north to south in each province
or district. Unless otherwise indicated, specimens are in the United States
National Musevun.

Alberta. 15 mi. above Smith Landing, 2; Fort Smith, 2 (1'); Smith Landing,
2; LaButte, Fitzgerald, 1'; Egg Lake, 15 mi. NW Ft. Chippewyan, 4 (2');
Lobstick Island, near Ft. Chippewyan, 1; Athabasca Delta, 9 mi. above mouth
of main branch, 1; Athabasca Delta, Long Creek, 1 mi. W of main branch,
2; Ft. Chippewyan, 1; Peace Point, 1'; 18 mi. below Peace Point, 1; Em-
barass River, 7 (4'); Athabasca River, 1'; Ft. McMurray, 1; Athabasca River,
Middle Rapid, 2; 60 mi. above Grand Rapids, 1; Boiler Rapid, 1; Entrance, 3';
St. Albert, 2.

British Columbia. Fort Halket, 1; Shesley, 1'; Dorothy Lake, Mts. W of Ft.
Nelson, 4000 ft., 3'; valley between Musqwa and Prophet rivers, 3800 ft., SW
of Ft. Nelson, 2^ Sikanni Chief Riv., 1; Telegraph Creek, 7 (6"); head of Bad
River, 2350 ft., on lake, 1; Sbc Mile, 5*; Tuchodi Lake, 2°; Iskoot River, 2°;
Level Mtn., 1'; head of Tatletuey Lake, 12 mi. W Thudade Lake, 2; Robb
Lake District, 5"; Ft. Grahame, 12 (2'); Sustut Mts., on trib. Sustu Riv., 25 mi.
SE Thudade Lake, 2; Laurier Pass, 1; Omineca Mts., 1"; Point Creek and
Clearwater River, 2; Kispiox Valley, 23 mi. N Hazehon, 5'; Hazelton, 3'; NW
arm Tacla Lake, 7; N end Babine Lake, 1; Pt. Simpson, 1; Metlakatla, 1; Stuart
Lake, 27; S Fk. Sahnon Riv., 1'; mouth Sahnon Riv., 1'; Vanderhoof,
4'; Wistaria P. O., near Bums Lake, 1'; Kruger Lake, 9'; Indianpoint Lake,
23'; Quesnel, 1; Ahbau Lake, 3'; Isaacs Lake, 6*; Beaver Pass, 56'; Lightning
Creek, 54'; LaFontaine, 16'; Barkerville, 1'; Barkerville District, 34'; Swift River,
27'; Cunningham Creek, 34'; Itcha Mts., 1'; Anahim Lake, 1'; Chezacut Lake,
8'; Kleena Kleene, 18'; 158 mi. House (Cariboo on labels), 3'; Rivers Inlet,
6 (5°; 1'); Horse Lake, 4=^ Kingcome Inlet, 8'; Loughborough Inlet, T; McGiUi-
vary Creek, 1; Camel Back, Pemberton Meadows, V; Arrow Rapids, mainland
opposite Stuart Island, 1'; Butte Inlet, 9'; Green Lake, 1'; Mt. Whistler,
r°; Alta Lake, 2 (F; 1"); Mons, 1^

Keewatin. Foot of Baker Lake, 1.

Labrador. Okak, 3=; Nain, 22 (11'; 11'); Hopedale, 24'; Kippokak Bay, 7';
Ailik, 1; Makkovik, 26^ Labrador, 55° N, 3; Hamilton Inlet, 2^ NW River
Post, interior Labrador, 5"; Cartwright, 5; Paradise, 12; Sandwich Bay ( Muddy
Bay, 6; North River, 6), 12; Battle Harbor, 1"; St. Marys River, 3''; Black
Bay, 16 ( 15''; 1^'); Lanceau Loup, 17 (1^).

Mackenzie. Ft. Frankhn, 1'; Ft. Rae, 12; Fairchild Point, 6"; Fort Simpson,
10 (2'); Hot Springs (61°, 125°), 1'; Willow River, near Ft. Providence, 1;
35 mi. N Big Island, 7; Big Island, 9; 3 mi. S Big Island, 7; Ft. Resolution, 9;
100 mi. N Ft. Smith, 2; 75 mi. NW Ft. Smith, 1; Ft. Liard, 2; Sucker Creek,
4'; Govt. Hay Camp, Wood Buffalo Park, 2\

Manitoba. Egg Is., Rabbit Point, 1; Ft. Churcliill, 1; Ft. York, W Hudsons
Bay 57° N, 1^^ Oxford House, 11; Gypsumville, 1"; Lake St. Martin.

New Brunswick. Restigouche Co.: Bird Bait, north Camp, 6 mi. NE Nictau
Lake, 2''; Red Brook, Tobique River, 1". Victoria Co.: Trousers Lake, 3*.
Glouchester Co.: Youghall, 1'; Miramichi Road, 15 mi. from Bathurst, 13".
York Co.: Scotch Lake, 2.

Newfoundland. Nicholsville, 3=; Bay St. George, 48 (26=; 2'=; 1"); Cod-
roy, 9 (7=; 2»).

Nova Scotia. Victoria County: Cape North, 2\ Inverness County: Fizzle-
ton, 3\ Richmond County: St. Peters, 1\ Pictou County: Glengary,
1". Guysborough County: East Roman Valley, 5'. Kings Co.: Wolfville,
5 (3', 2'); near Wolfville, l\ Halifax Co.: Hammond Plains, 1. Annapolis Co.:
AnnapoUs Royal, 1. Digby Co.: Digby, 3. No locality more definite than
Nova Scotia, 3.

118

University of Kansas Publs., Mus. Nat. Hist,

Ontario. Severn River, 1'; R. C. Mission, Yellow Creek, near mouth of
Albany, 2'°; Ft. Albany, 4; Charlton Island, 1; Moose Factory, 10 (7";
3'); Abitibi, 1".

Quebec. Fort Chimo, 10'; Ungava Forks, 1; Belcher Islands, Hudsons Bay
(Tukarak Island, 29; Eskimo Harbor, 2; InnetalUng Island, 1; S tip Gibson
Peninsula, 2; Flaherty Island, 1), 35'*; Cairn Island, Richmond Gulf, 2";
Manitounuk Sound, 4"; about 15 mi. S Great Whale River, 1"; Ft. George,
1"; Charlton Island, 1"; Waswonaby Post, 1'; Mistassinnay Post, 3'; Godbout,
36; Mt. Albert, 7 (4'^ 3'); St. Anne River, 1500 ft., 1'; Ste. Anne des Monts,
3'; "Federal Mine", 1'; Berry Mountain Camp, 1'; Berry Mountain Brook, 1';
Cascapedia River (Middle Camp, 2; Tracadie, 2; Square Forks, 1), 5'.

Saskatchewan. Poplar Point, Athabasca Lake, l""; Fair Point, Athabasca
Lake, 1"; Emma Lake, 1*; Harper Lake, 2'; Livelong, 3"°; Fairholm, 2*; Touch-
wood Hills, 2'^ Indian Head, 1'".

Yukon. Hoole Canyon, 1; Teslin Lake (30 mi. N of , 1; Lake itself, 1; "near"
the lake, 1; Mts. "near", 2; Snowden Mts., 2; Teslin Post, 2; Eagle Bay, 1;
Morley Bay, 2; NisutUn River, 1; NisutUn Flats, 2; Wolf River, 1; Wolf Lake,

5), 2r.

Mustela erminea cicognanii Bonaparte

Ermine

Plates 2, 3, 4, 9, 10 and 11

Mustela cigognanii [sic] Bonaparte, Charlesworth's Mag. Nat. Hist., 2:37,

1838.
Putoritts vulgaris, Emmons, Quadrupeds of Massachusetts, p. 44, 1840.
Mustela pusilla DeKay, Zool. of New York, Pt. 1, Mammalia, p. 34, pi.

14, fig. 1, 1842. Type from New York State.
Putorius pusillus, Audubon and Bachman, Vivip. Quadrupeds of N. Amer.,

2:100, pi. 64, 1851 (pi. 1846) and erroneously labled Mustela fusea,

as pointed out on p. 102 of te.\t.
Putorius cicognanii, Baird, Mamm. N. Amer., p. 161, 1858.
Putorius richardsoni cicognani. Bangs, Proc. Biol. Soc. Washington, 10;

18, fie;s. 4, 4a of pis. 1 and 2, and pi. 3, figs. 2, 2a, February 25,

1896 (part).
Putorius cicognani, Merriam, N. Amer. Fauna, 11:10, pi. 2, figs. 3, 3a,

4, 4a and pi. 5, figs. 2, 2a, June 30, 1896.
Mustela cicognanii cicognanii. Miller, U. S. Nat. Mus. Bull., 79:95, Decem-
ber 31, 1912; Bishop, Joum. Mamm., 4:26, February 9, 1923.
Mustela cicognanii, Jackson, Joum. Mamm., 3:15, February 8, 1922.
Mustela erminea cicognanii. Hall, Joum. Mamm., 26:77, February 27,

1945; Hall, Joum. Mamm., 26:180, July 19, 1945.

Type. — No type specimen designated; type locality, eastern United States.

The restriction of the type locahty from the general region of northeastem
North America, as given by Merriam (1896:10) to the less inclusive area
of the eastern United States as earlier given by Bangs (1896:18) is supported

1. Canadian National Museum 12.

2. Museum of Comparative Zoology 13.

3. American Mus. Nat. History 14.

4. Mus. Vert. Zool., Univ. California 15.

5. Collection of Alex Walker 17.

6. Provincial Museum of Brit. Columbia 18.

7. Collection of Kenneth Racey 19.

8. Field Museum of Natmal History

9. Univ. Washington Museum of Zoology 20.

10. Collection of Ian McTaggart-Cowan 21.

11. Acad. Nat. Sciences of Philadelphia

British Museum of Natural History
Museum of Zoology, Univ. Michigan
Carnegie Museum
Royal Ontario Museum of Zoology
Donald R. Dickey Collection
Berlin Zoological Museum
Natm-historika Ricksmuseum,

Sweden
Collection of William T. Shav/
Collection of J. A. Munro

MUSTELA ERMINEA 119

by Bonaparte's remarks in connection with the proposal of the name cicog-
TUinii. He says (1838:37-38) "During my stay in the United States, I only
saw a small species of Mustela, very common throughout the Union . . .".
This animal constituted basis for the name cicognanii which name, he points
out, is bestowed in order that the Americans "... should have con-
stantly under their eye, this very common little animal, as the perpetual
memorial . . ." to the Italian Governmental representative ". . . who,
for upwards of fourteen years had served, in diplomatic and commercial
concerns, . . . two countries, ... so diflFerent ... as the
Roman and the United States . . . ." Clearly he had in mind principally,
if not exclusively, the animal of tlie United States.

Range. — Transition and higher life-zones of northeastern United States
south to Connecticut, central Pennsylvania and extreme northeastern Ohio;
in Quebec and Ontario westward from the latitude of central Maine to Lake
Nipigon and Lake of the Woods. See figure 25 on page 95.

Characters for ready recognition. — DiflFers from M. e. richardsonii of both
sexes, in that least width of color of underparts averages less than a third
rather than two-fifths of greatest width of color of upper parts, in males
skull less, instead of more, than 1.9 grams and basilar length less than 38,
in females by 16 per cent hghter skull (0.92 versus 1.1 grams); from M. e.
hangsi, in males hind foot less instead of more than 40, hnear measurements
of skull averaging 11 per cent less (depth of skull at plane of molars 10.0
versus 11.4), in females averaging smaller, hind foot 30 versus 32 and depth
of skull at plane of molars 8.6 versus 9.1.

Description. — Size. — Male. Seven adults and subadults from New York
and Pennsylvania, yield average and extreme measurements as follows: Total
length, 266 (240-295); length of tail, 74 (66-80); length of hind foot, 36
(33-39). Hamilton (1933:294) gives the weight of 31 adults from New York
as 81 (66-105) grams.

Female: Twelve adults and subadults from Maine and the area south to
central Pennsylvania, yield average and extreme measurements as follows:
Total length, 243 (225-260); length of tail, 63 (55-72); length of hind foot,
29.8 (26-32). Hamilton (1933:294) gives the weight of 15 adults from New
York as 54 (45-71) grams.

Color. — As described in Mustela erminea richardsonii except that under-
parts in summer Marguerite Yellow or even more whitish; least width of color of
underparts averaging, in adult males from New York and Pennsylvania, 29
(27-32) per cent of greatest width of color of upper parts. Black tip of tail
in same series averaging 42 (30-51) mm. which is 57 per cent of length of tail-
vertebrae.

Skull. — Male ( illustrated by 4 adults in table of cranial measurements, which
see): See plates 2-4. As described in Mustela erminea richardsonii except
that: Weight, 1.5 (1.2-1.7) grams; basilar length, 35.7 (33.8-37.6).

Female (illustrated by adult and subadults recorded in table of cranial
measurements, which see): See plates 9-11. As described in Mustela erminea
richardsonii except that: Weight of 2 subadults, 0.92 (0.86-0.98) grams;
basilar length, 32.4 (31.4-33.3).

120 University of Kansas Publs., Mus. Nat. Hist.

The skull of the male, in linear measurements, is approximately
13 (12-16) per cent smaller and 40 per cent lighter than in M, e.
richardsonii. In relation to the basilar length, the skull averages
slightly narrower, slightly shallower as measured in the vertical
plane touching the posterior borders of the last upper molars, and
the preorbital part is shghtly longer. In skulls of females of
cicognanii, linear measurements average 3(0-6) per cent less, the
weight is 16 per cent less and tlie teeth are 5 per cent shorter.
In relation to the basilar length, measurements of the skull are
approximately the same or slightly less in cicognanii.

In comparison with bangsi, the male sex in linear measurements
of the skull and teeth averages 11 per cent less than in bangsi from
Aitkin, Minn., and 6 per cent less than in bangsi from Elk River,
but in relation to the basilar length the preorbital region is larger.
The weight is approximately a fourth less. In females the measure-
ments average less, some being the same, and in relation to the
basilar length, the bullae are shorter and the skull is shallower.
The weight is about the same.

Remarks. — In January, 1838, in Charlesworth's Magazine of Nat-
ural History, C. L. Bonaparte proposed for three kinds of American
weasels the names Mustela cicognanii, Mtistela richardsonii and
Mustela longicauda.

In this paper Bonaparte indicates that he previously had written
(for his Iconografia della Fauna Italica . . .) an account of Mus-
tela cicognanii using this same name. Fasciola XXII of the Iconogr.
d. Fauna Italica, presenting his account of Mustela, like the Eng-
lish paper was published in the year 1838. In his article in Charles-
worth's Magazine, Bonaparte refers to his book published [used
the past tense] in Rome but whether it actually appeared first I
am unable to determine and hence am uncertain which of the two
constitutes the original description.

Reference to the Italian account suggests as basis for the name
M. cicognanii, (1) specimens possibly seen in tlie United States
by Bonaparte, or (2) Godman's published account of the animal.

In the English publication, however, Bonaparte actually says
that (1) he saw the small species in the Union [= United States].
Also, he (2) mentions his earlier written Italian account, (3) men-
tions that "all the [American?] naturalists" used the name M. vul-
garis for this animal, (4) incidentally mentions Godman's account,
and (5) in naming two other American species cites accounts of
them by Richardson. Also, Bonaparte in this English article makes

MUSTELA ERMINEA 121

clear that when he wrote [not necessarily published] his Italian
paper he did not know of the existence of two of the three American
species.

In the register of mammals at the British Museum of Natural
History, tliere appears:

43.3.3.3 Mustek longicauda Bonap N amer presented by Dr. J. Richardson

4 Mustek Richardsonii Bonap "

5 " Cicognanii Bonap "

To the right of these entries there appears, in three lines, the
notation: "The three specimens examined by Prince Canino on
which he established the three species"

Every part of each of the above entries is in the hand writing
of J. E. Gray, in charge of the collections from 1824 to 1840 and
associated with them as Keeper until 1875, The three specimens
are in good condition considering their age. The catalogue or
register number shows, among other things, that they were entered
in the register on March 3, 1843,

Questions which might occur to anyone are:

(1) Was there a type specimen of Mustela Cicognanii Bonaparte?
If so is it no. 43.3.3.5?

(2) If there was no type specimen was there a type locality? If
so what is it?

Among other things that may have bearing on these questions,
are these: Bonaparte in Charlesworth's Magazine appears to base
the two names Mustela Richardsonii and Mustela longicauda on
Richardson's published account of Mustela erminea. At any rate
immediately following each of the two names, Bonaparte writes
"Nob. (M, erminea Rich, F, Bor, Amer,)," Bonaparte's other,
first newly proposed name, Mustela Cicognanii, in Charlesworth's
Magazine has following it only "Nob, North America", although
in a paragraph above he did point out that this was the animal
which all naturalists, at the time he was in America, considered as
M. vulgaris.

Turning to Richardson's account (Fauna Boreali Americana,
, . , Quadrupeds, pp. 45-47, 1829) one finds that he recognized
two species, M, vulgaris and M, erminea. Of the first he gives
measurements "of an old female killed at Carlton House," Of the
second species he distinguishes two varieties, the first represented
by a specimen, of which he gives measurements, 'Tailed at Fort
Franklin, Great Bear Lake" and, the second variety "of a larger
size, having a longer tail and longer fore-claws" he indicates the

122 University of Kansas Publs., Mus. Nat. Hist.

size of by giving measurements of a specimen taken "in the neigh-
borhood of Carlton House."

The last variety is clearly the basis of Bonaparte's M . longicauda.
The specimen from which Richardson took his measurements I
have been unable to locate [no. 43.3.3.3 in the British Museum,
appears to be another specimen, although of the same subspecies
and provided by Richardson].

The first variety of Richardson's Mustela erminea, clearly is the
basis of Bonaparte's M. Richardsonii. The specimen from which
Richardson took his measurements may well be no. 43.3.3.4 now
preserved in the British Museum of Natural History, but I could
not be certain about this.

Richardson's M. vidgaris is accompanied by measurements of a
female which I have ascertained to my full satisfaction is the
identical specimen now bearing catalogue number 43.3.3.5 said
by Gray to be the specimen on which Bonaparte based his name
Mustela cicognanii.

Gray probably saw his guest, Bonaparte, at work on these weasels
and Gray's own written indication perhaps should be accepted at
its face value. I found only 4 Richardson specimens of North
American weasel in the British Museum in 1937 and it is con-
ceivable that Bonaparte, 100 years before, actually had at hand
only one specimen each of two kinds and 2 specimens of the third.
This I think is not an important consideration, though, for Gray
says just which specimens did serve as basis for Bonaparte's names
and there is only one specimen for each name according to Gray.

But I wonder if a type specimen can be made in this way? That
is to say, after a name is published in a manner which makes it
available, and if two or more specimens of the kind of animal in-
volved, were, or may have been, available to the describer, can a
person, even the author, himself, make a type specimen by saying
that one particular specimen is beyond doubt the specimen on
which a given name was established even though no particular
specimen was designated in the original description? I incline to
the view that a specimen so designated would at most be only a
lectotype, unless it were a "cotype.

However, if a holotype can be made by action such as Gray took,
then (1) is no. 43.3.3.3 the type specimen of Mustela longicauda
Bonaparte and, (2) is no. 43.3.3.4 the type specimen of Mustela
Richardsonii Bonaparte?

Incidentally, Mustela longicauda Bonaparte whether based on
no. 43.3.3.3 or on Richardson's account will continue in its present

MUSTELA ERMINEA 123

application. The same is true of Mustela richardsonii. If the basis
of Mustela cicognanii Bonaparte [the diagnosis in the Iconografia
d. Fauna Itahca . . . makes it clear that the name applies to the
short-tailed species] was a weasel from the eastern United States
or a description of a weasel or weasels from there, the name will
continue in its present application. If, instead, the name is based
on no. 43.3.3.3 (from Carlton House, Saskatchewan) or on Richard-
son's account of M. vulgaris, the name will apply to a diflFerent
subspecies (now called richardsonii and richardsonii will fall as a
synonym of cicognanii) and the ermine of the eastern United
States will take the next available name. Bonaparte probably
named (in manuscript at least) cicognanii before he ever saw the
specimen in the British Museum. This is indicated by his state-
ment in Charlesworth's Magazine (1838:37) that "I have now
[ItaHcs mine] found two [other] American species . . .". Whereas
the names richardsonii and longicauda are based on Richardson,
the name cicognanii, even if it dates from the account in Charles-
worth's Magazine, appears to have a composite basis composed at
the very least of (1) animals seen by Bonaparte in the United
States, and (2) those called vulgaris by some other authors. Con-
ceivably the specimen no. 43.3.3.3 in the British Museum, was part
of the basis. From the nature of the case it can be argued that
there could be no type and that if someone should bring to light
a specimen in, say, Philadelphia, bearing the notation "this is the
specimen seen in the United States by Bonaparte" it would im-
mediately become as important as the one in London. Any Ameri-
can weasel or weasels (then alive or preserved in a zoological col-
lection) that Bonaparte saw in the United States probably were of
the eastern United States. Bangs (1896:18-21), for one, previous
to the present consideration of the name cicognanii, restricted it to
the ermine of the eastern United States. Consequently, the name
cicognanii, in the present account is applied to the ermine of the
eastern United States. In my opinion there was and is no type.
Almost certainly there was no type if the Fauna Italica appeared
before the account in Charlesworth's Magazine did.

Specimens examined. — Total number, 172, arranged alphabetically by prov-
inces and states, then (except where indication is given to the contrary) by
counties from north to south within each state or province. Unless otherwise
indicated, specimens are in the U. S. National Museum.

Connecticut. Windham Co.: S. Woodstock, Woodstock Lake, V. Hartford
Co.: Windsor, 1'. New London Co.: Liberty Hill, 3'.

Maine. Aroostook Co.: Quimby, 1^ Ashland 2\ Piscataquis Co.: table-
land on top of Mt. Katahdin, 1; Chimney Pond, 3; T. 5, R. 13, 3^; "vicinity of
Chesnucook," 1"; T. 4, R. 13, 1'; Moosehead Lake, T; Grenville, 10"; Barnard,

124 University of Kansas Publs., Mus. Nat. Hist.

3 (1"). Penobscot Co.: South Twin Lake, 1'; Lincoln, 11 (7*, 2°, 2').
Franklin Co.: Seven Pond Township, 7'. Oxford Co.: Umbago Lake, T;
Upton, 4'; Bethel, 1'. Hancock Co.: Bucksport, 17'; Naskeag, 1. Lincoln Co.:
Booth Bay, 1=.

Massachusetts. Middlesex County: Wilmington, 2; Budington, 6 (1');
Worcester Co.: Cambridge, 5 ( 1', 3'); Sterling, V. Plymouth Co.: Middle-
boro, 7 (1').

New Hampshire. Carroll Co.: Ossipee, 5. Rockingham Co.: Greenland, 1'.
Cheshire Co.: Dublin, 1.

New York. St. Lawrence County: Ogdensburg, 1'°. Franklin Co.: Malone,
1". Lewis Co.: Locust Grove, 1. Warren Co.: Lake George, 1. Mont-
gomery Co.: Amsterdam, 1. Albany Co.: Albany, 1". Renesselaer County:
Berlin, 2'; Schoharie, V. Thompkins Co.: Cascadilla Creek, Ithaca,
1". Allegany Co.: Ford Brook, Wellsville, 1". Ontario Co.: Phelps, 1'.
Cattaraugus Co.: Cattaraugus, 1*.

Ontario (locahties locally north to south, then west to east). Thunder Bay
Dist.: Grand Bay, Lake Nipigon, 5'; Macdiamiid, 2"; Oscar, 2°; 20 mi. SW
Fort Wilhams, 1'; Michipicoten Island, 3°. Algoma Dist.: Michipicoten, 1;
Franz, 1"; Pancake Bay, 2". Parry Sound Dist.: French River, Georgia Bay,
1^; Seguin Falls, Tvi^). Montieth, 1". Sudbury Dist.: Casselmans, Rathbun
Twp., 1*. Nipissing Dist.: Smoky Falls, near Kapuskasing, 4'; Franks Bay,
Lake Nipissing, 1\ Haliburton Co.: Gooderham, 1''. Simcoe County: OrilUa,
1'; no locaHty more definite than county, T". Carelton Co.: Britannia, 5 mi.
W Ottawa, 1"; Ottawa, 1"; Constant Bay, NE? of Ottawa, 1". Wellington
Co.: Mt. Forest, 2"; Guelph, 1". Addington Co.: Buckshot Lake, Abinger
Twp., P. Fontenac Co.: Clearlake, Arden, 1".

Pennsylvania (by counties from west to east). Crawford Co.: North She-
nango Township, Pymatuning Swamp, 2'*; Linesville (3 mi. NW, 1; 3)2 mi. W,
2; 3 mi. W, 1; 2 mi. SW, 1; 7)i mi. SW, 1) &\ Potter County: Cherry Springs
Farm, Abbott Township, 1; 3 mi. S Inez, South Fork Simamahoning Creek, 1".
Sullivan County: Lopez, 1". Lackawana Co.: Scranton, l\ Wayne County:
Waymart, 1.

Quebec (west to east). Labelle County: Kamika [z= Kiamika] Lake, 2";
Lacoste, 2"; Trout Lake, probably in this county, 2". Megantic Co.: Black
Lake, 1".

Rhode Island. Newport Co.: Middletown, 2".

Vermont. Lamoille Co.: Mt. Mansfield, 1. Windsor Co.: Barnard, V.

Mustela erminea bangsi Hall

Ermine

Plates 2, 3, 4, 9, 10 and 11

Mustela erminea bangsi Hall, Journ. Mamm., 26:176, July 19, 1945.
[Putorius] cicognani, Meams, Bull. Amer. Mus. Nat. Hist., 3:235, June 5,

1891.
Putorius richardsoni cicognani. Bangs, Proc. Biol. Soc. Washington, 10:18,

February 25, 1896 (part).
Putorius cicognanii, Cory, NIamm. Illinois and Wisconsin, p. 375, 1912.
Mustela cicognanii, Aldous and Manweiler, Journ. Mamm., 23:250, August

13, 1942.

1. American Mus. Nat. History 9. University of Wisconsin

2. Boston Society of Natural History 10. Mus. Vert. Zobl., Univ. California

3. Museum of Comparative Zoology II. Canadian National Museum

4. Acad. Nat. Sciences of Philadelphia 12. Field Museum of Natural History

5. Collection of Alex Walker 13. Collection of Kenneth Racey

6. Collection of W. E. Snyder 14. Carnegie Museum

7. Museum of Zoology, Univ. Michigan 15. Cornell University

8. Royal Ontario Mtiseum of Zoology 16. Nevi' York State Museum

MUSTELA ERMINEA 125

Mustela cicognanii cicognanii, Bailey, N. Amer. Fauna, 49:169, January 8,
1927; Leraas, Joum. Mamm., 23:344, August 13, 1942.

Type. — Male, subadult, skull and skin; no. 11541, D. R. Dickey Coll.;
Elk River, Sherburne County, Minnesota; November 1, 1925; obtained by
Bernard Bailey, original no. A 606.

The skull is complete and the teeth all are present and entire. The skin
is well made and in a good state of preservation.

Range. — Southern Manitoba, northeastern North Dakota, the whole of
Mirmesota, Wisconsin and Michigan and northern Iowa. See figure 25 on
page 95.

Characters for ready recognition. — Differs from M. e. richardsonii, in that,
in both sexes, least wadth of color of underparts averages about a third, in-
stead of two-fifths, of greatest width of color of upper parts, and in that
skulls of males are a fifth or more lighter, basilar length averaging less than
40; from M. e. cicognanii, in tliat hind foot more than 40 in males, averaging
32 versus 30 in females, and in larger skull, depth of skull at plane of molars
being 11.4 versus 10.0 in males and 9.1 versus 8.6 in females.

Description. — Size. — Male: Twelve adult and subadult males from Aitkin,
Minnesota, yield average and extreme measurements as follows: Total length,
316 (291-341); length of tail, 87 (70-101); length of hind foot, 43 (40-
44). Two adidts from Aitkin each weigh 170 grams.

Four adult and subadult females from Elk River and Fort Snelling,
Minnesota, yield average and extreme measurements as follows: Total length,
249 (240-260); length of tail, 61 (55-65); length of hind foot, 32 (30-33).

Color. — As described in Mustela erminea richardsonii except that, least
width of color of underparts averaging, in males from Minnesota, 32 ( 19-
51) per cent of greatest widtli of color of upper parts. Black tip of tail in
12 male topotypes in white winter pelage averaging 52 (45-58) mm. which
is 60 (53-66) per cent of length of tail-vertebrae.

Skidl. — Male (based on adults from Aitkin): See measurements and plates
2-4. As described in Mustela erminea richardsonii except that: Weight of
2 adults from Aitkin, 2.2, 2.3 grams (9 subadults from T. 61 N, R. 26 W,
average 1.95 grams); basilar length, 39.7 (38.5-40.7); length of tooth-rows
rarely more (usually less) than length of tympanic bulla.

Female (based on adults from Minnesota as listed in table of cranial
measurements, which see): See plates 9-11. As described in Mustela
erminea richardsonii except that: Weight, of a subadult from T. 61 N, R. 26
W, 0.91 grams; basilar length, 32.8 (31.8-33.6); breadth of rostrum rarely
equal to as much as 30 per cent of basilar length.

From richardsonii, topotypes of bangsi differ in that cranial
measurements in males are approximately 7 (5-9) per cent less,
linear measurements of teeth are 10 (9-11) per cent less and the
skull is a fifth lighter. In relation to basilar length the tympanic
bullae of bangsi are longer. Skulls of females are individually in-
distinguishable, those of bangsi averaging approximately 1 per
cent less in linear measurements. Comparison with the smaller
cicognanii is made in the account of that subspecies.

126 University of Kansas Publs., Mus. Nat. Hist.

Remarks. — Before the subspecific name bangsi was proposed,
individuals of this subspecies ordinarily were recorded in the
hterature as Mustela cicognanii. The best single lot of material
is in the zoological collection of the University of Wisconsin. The
late naturalist Albert Lano preserved a large share of the material
from Minnesota. The large series from Elk River of that same
state was mostly collected by Bernard Bailey although his Aunt,
Anna (Bailey) Mills, and her brother the late Vernon Bailey, at
an earlier time saved some specimens from Elk River. The name
bangsi was proposed in recognition of the superior work done on
American weasels by the late Outram Bangs,

From the range of M. e. invicta in the Rocky Mountains, that
of bangsi is separated by the Great Plains from a large part of which
region the species is unknown. M. e. bangsi differs from invicta in
greater degree of sexual dimorphism in size, and in each sex by
larger size, narrower light-colored underparts, and deeper brain-
case as measured at the anterior margin of the basioccipital. In
bangsi the braincase is deeper relative to the length of the skull
as well as, of course, actually deeper.

Of the two subspecies whose ranges do meet that of bangsi, it
more closely resembles richardsonii than cicognanii. From rich-
ardsonii, especially from southeastern populations of the same in
which the skull is of the same size as in bangsi, the latter differs in
longer hind feet. This is an average difference and by one inter-
pretation the animals here referred to bangsi might be lumped with
some of the populations from the southeastern part of the range
of richardsonii and the whole lot treated as intergrades between
richardsonii and cicognanii. Nevertheless, the animals here re-
ferred to bangsi are not geographically intermediate between rich-
ardsonii and cicognanii and this consideration had much to do
with the decision to recognize as a separate subspecies the animals
here named bangsi.

Within the range of the subspecies there is some geographic
variation; the hind feet of animals from Iowa average slightly
shorter than those of animals from Minnesota and Wisconsin but
are nowhere nearly so short as in cicognanii at the same latitude in
the eastern United States.

It is noteworthy that the few specimens seen from Isle Royal
have the long hind feet of bangsi and not the short hind feet of
cicognanii which occurs all along the northern mainland.

Because an oft cited record of occurrence even though erroneous,
has a way of being repeated in later works, attention is here called

MUSTELA ERMINEA 127

to the alleged occurrence of this ermine in northwestern Ohio at
New Bremen. Henninger (1921:239) published the original ac-
count of the supposed occurrence but as I pointed out in 1937
(p. 304), the specimen concerned proved upon examination to be
a female of Mustela frenata noveboracensis. Henninger was mis-
led probably by the short tail; the end of the tail had been lost
and healed over before the animal's death. The present study has
revealed that M. erminea everywhere east of the Cascade Moun-
tains assumes a white winter coat. Had this been known when
Henninger obtained his specimen he probably would not have
wrongly identified the animal from New Bremen which was in the
brown, winter pelage.

Specimens examined. — Total number, 222, arranged alphabetically by prov-
inces and states and, arranged from north to south, by counties in each state.
Unless otherwise indicated, specimens are in the University of Wisconsin
Museum of Zoology.

Iowa. Dickinson County: W side Lake Okobogie, V. Winnebago County:
Lake Mills, 7'. Worth County: Northwood, 1'. Clay County: "Dewey's
Pasture, near Ruthven", 1'.

Manitoba. Aweme, 4*; Red River Settlement, 1°.

Michigan. Isle Royal: Tobin Harbor, P; Bell Isle, 1^ Washington Harbor,
3'. Ontonagon Co.: Ontonagon, 2 ( 1', 1'); T 51N, R 43W, sl7, Porcupine
Mts., 1'. Gogebic County: Little Girls Point, 5'; Ironwood, V. Iron County:
no locahty more definite than county, 1^. Luce Co.: Taquahniemenaw River
Falls, V. Chippewa Co.: Sault Ste. Marie, 2\ Emmet County: Wilderness
State Park, 2\ Cheboygan County: Univ. Mich. Biol. Station, 1'. Washtenaw
Co.: Ann Arbor, 1^.

Minnesota. Kittson County: no locahty more definite than county, 1'.
Roseau County: Deer Township, 1°; Falun Township, 2°. Marshall Co.?:
Moose River, 5°; Warren, definitely in Marshall County, 1°. Cook County:
Grand Marais, 3 (2', V). St. Louis County: 2 mi E Babbit, 14"; Bumtside
[z= Bumside] Lake, 1°. Itasca County: T 61N, R 26W, 23. Clay Co.: Moor-
head, 3". Aitkin Co.: Aidcin, 13 (11", 1", 1"). OUer Tail Co.: Arthur,
3"; Ten Mile Lake, 1'; Parkers Prairie, 2". Chisago Co.: North Branch,
1". Sherburne Co.: Elk River, 42 ( 16^ 5^ 20', 1^°). Hennepen Co.: Lake
Minnetonka, 1"; MinneapoHs, 1°; Fort Snelling, 5 (4", 1").

North Dakota. Pembina Co.: Walhalla, V. Nelson Co.: Stump Lake, 1°.
Eddy Co.: Brantford, 2\

Wisconsin. Douglas County: T. 44N, R. 13W, 1; Gordon, 1. Bayfield Co.:
Brinks Camp, Washburn, 1^ "near Cable", 1. Ashland County: Bear Lake, 2.
Iron County: Fisher Lake, 4; Mercer, 5. Vilas Co.: Mamie Lake, 16°; Ox
Bow Lake, 1''. Oneida Co.: Tomahawk Lake, 1". Langlade County: T. 34N,
R. HE, 3. Rush Co.: Ladysmith, 1. Dunn County: Colfax, 2. Door County:
Mink River, ElHson Bay, 1'. Dodge Co.: Fox Lake, 1"; Beaver Dam, 12".

1. Collection of T. C. Stephens 9. Univ. Kansas Mus. Nat. History

2. Iowa State College 10. Carnegie Museum

3. Museum of Zoology, Univ. Michigan 11. Field Museum of Natural History

4. Collection of Stuart Griddle 12. British Museum of Natural History

5. United States National Museum 13. Berlin Zoological Museum

6. Collection of Alex Walker 14. Museum of Comparative Zoology

7. Donald R. Dickey Collection 15. Mus. Vert. Zool., Univ. California

8. American Mus. Nat. History 16. Collection of W. E. Snyder

128 University of Kansas Publs., Mus. Nat. Hist.

Mustela erminea invicta Hall

Ermine

Plates 2, 3, 4, 9, 10, 11 and 41

Mustela erminea invicta Hall, Joum. Mamm., 26:75, February 27, 1945;

Hall, Joum. Mamm., 26:180, July 19, 1945.
Putorius cicognanii, Preble, N. Amer. Fauna, 27:230, October 26, 1908.

Type. — Male, subadult, skuU and skin; no. 101122, Mus. Vert. Zool.; Bene-
wah, Benewah County, Idaho; October 24, 1926; obtained by William T. Shaw.

The skull has a hole in the right squamosal bone on the floor of the braincase,
and lacks the hamular process of the left pterygoid. The postmolar part of the
right lower jaw is missing. The teeth all are present and entire. The skin is in
white, winter pelage, well made, and in a good state of preservation.

Range. — Central Rocky Mountain region from Jasper Park south over Al-
berta, southeastern British Columbia, Washington east of the Cascades, and
north and central Idaho and northwestern Montana. See figure 25 on page 95.

Characters for ready recognition. — Differs from M. e. richardsonii, in males,
by skull Hghter than 1.9 grams, mastoid breadth less than 19.9, depth of skull
at anterior margin of basioccipital less than 12.4, in females by corresponding
measurement of depth less than 10.1, and weight of skull less than one gram;
from M. e. fallenda, in both sexes, by upper lips white ( not brown ) in males by
skull averaging longer (37.0 versus 35.7), in females by breadth of rostrum less,
instead of more, than 30 percent of basilar length; from M. e. streatori, gulosa,
and muricus by hind foot more than 36 and basilar length more than 35 in
males and by hind foot more than 29.5 and basilar length more than 30.5 in
females; further distinguished from streatori by white (not brown) upper lips
and from gulosa by black tip of tail more than half length of tail-vertebrae.

Description. — Size. — Male: Ten adults and subadults from central Idaho
County yield average and extreme measurements as follows: Total length, 291
(272-328); length of tail, 86 (75-100); length of hind foot, 39.9 (38-44).

Female: Five adults and subadults from the same locality yield average
and extreme measurements as follows: Total length, 255 (245-270); length of
tail, 71 (68-76); length of hind foot, 32.3 (32-33).

Color. — As described in Mustela erminea richardsonii except that under-
parts in summer Marguerite Yellow or more whitish; least width of color of
underparts averaging, in four females from Idaho and Montana, 38 ( 33-43 ) per
cent of greatest width of color of upper parts. Black tip of tail in same speci-
mens 38 (31-42) mm. which is 57 (52-65) per cent of length of tail-vertebrae.

Skull. — Male ( 5 adults from Idaho County ) : See measurements and plates
2-4. As described in Mustela erminea richardsonii e.xcept that: Weight, 1.5
(1.4-1.7) grams; basilar length, 37.0 (35.8-39.8).

Female (illustrated by adult and 4 subadults in table of cranial measure-
ments, which see): See plates 9-11. As described in Mustela erminea richard-
sonii except that: Weight, 0.72 (0.7-0.9) grams; basilar length, 32.2 (31.6-
32.8).

From fallenda, invicta differs in that the skull of the male has a
relatively narrower rostrum and relatively shallower braincase. Fe-
males show the same differences but the degree of difference is about

MUSTELA ERMINEA 129

as great again as in males. The teetli are almost exactly the same
size in the two subspecies. The weight is the same in males but in
females invicta is 18 per cent heavier.

From streatori, invicta differs in that males average larger in every
measurement taken except that the anteroposterior diameter of the
inner moiety of Ml is less; 36 per cent heavier; linear measurements
of the skull are about 5 per cent larger and those of the teeth, with
the one exception noted, about 6 per cent larger; relative to the
basilar length the tympanic bullae are longer and the rostrum is
relatively narrower. In females, measurements of the skull average
8 per cent more and those of the teeth 7 per cent more except that,
as in males, the inner lobe of Ml is actually shorter. Females of
invicta are 12 per cent heavier; relative to tlie basilar length the skull
is narrower throughout and the tooth-rows are shorter than in
streatori.

From gulosa, invicta differs in that males average larger (about
12 per cent) in every measurement taken, excepting the antero-
posterior diameter of Ml which is the same; 50 per cent heavier;
relative to the basilar lengdi the length of the tooth-rows and inter-
orbital breadth are less. In females the inner lobe of Ml is smaller
but every other measurement taken of the skull and teeth is more,
invicta averaging about 8 per cent larger and 22 per cent heavier;
relative to the basilar length, the tooth-rows are shorter and the
skull is narrower interorbitally, through the rostrum and across the
zygomata.

From murica, invicta of corresponding sex differs in being larger
in every measurement taken; males average 17 per cent larger in
cranial measurements, 13 per cent larger in dental measurements
and are 83 per cent heavier; corresponding percentages for females
are 11, 9 and 20. Exception must again be made for the antero-
posterior diameter of the inner lobe of the last upper molar which is
less in females, and only slightly more in males. In males of invicta
the tympanic bullae are longer in relation to the basilar length.
From the geographically remote cicognanii, skulls of both males
and females of invicta are to me individually indistinguishable.
There is, nevertheless, an average difference not apparent to the
eye between skulls of males. If the length of the tooth-rows be
taken as a standard (100 per cent), the rostrum, of invicta, as
measured across the lacrimal processes is broader (89 rather than
84 per cent ) but the width across the fourth upper premolars is less,
94 rather tlian 97 per cent of the length of die tooth-rows.

5—3758

130 University of Kansas Publs., Mus. Nat. Hist.

Since the skull of invicta closely resembles that of cicognanii, it
follows that invicta differs from richardsonii and bangsi in about
the manner described in the account of cicognanii.

Remarks. — Animals of this subspecies in advance of the present
study generally were recorded in the literature under the name
Mustela cicognanii. The difficulty in distinguishing individual
specimens of invicta on morphological grounds from those of the
geographically remote M. e. cicognanii should not be taken to in-
dicate that the populations do not differ appreciably. Actually
they differ in several characters although in no one of these is the
degree of difference sufficient to allow of using it alone as a certain
means of diagnosis. In invicta, as compared with cicognanii, the
light-colored underparts are wider in relation to the dark-colored
upper parts and the tail is longer by 4 per cent relative to the head
and body. Given a population of each of the two subspecies, in
which the skull is of the same mass, the hind feet are longer in
invicta, there is more sexual dimorphism in size, and the anterior
part of the skull differs in some particulars as just described in the
comparison of the skull of invicta with other forms. Nevertheless,
each of these differences is of an average sort. Therefore, and
because over-all size is about the same in the two subspecies con-
cerned, one or a few specimens from, say, central Idaho, can be
distinguished from animals from western Pennsylvania only with
difficulty, if at all. The close resemblance of skulls of invicta and
cicognanii may be a function of their living at approximately the
same latitudinal position in a climate that has marked seasonal
variation.

Intergradation with richardsonii is complete and gradual; in one
sense invicta is but little more than a small richardsonii. Inter-
gradation with fallenda is shown by several specimens. These two
races differ in large degree in color, and in size and shape of the
skull of females. Although the geographic area where intergrada-
tion in color occurs is fairly wide, the area in which intergradation
in cranial characters in females occurs, appears, from the in-
adequate material available, to be much narrower. Intergradation
occurs freely in Washington with streatori but with muricus so far as
known only in the Bitterroot and nearby mountains of northwestern
Montana. The Snake River Plains and low country along much of
the Columbia River appears to be uninhabited by weasels of the
species erminea and hence there is opportunity for intergradation
only in the mentioned area of Montana.

MUSTELA ERMINEA 131

Specimens examined. — Total number, 177, as follows. Arranged alpha-
betically by provinces and states then by localities from north to south in
each province and by counties from north to south in each state. Unless
otherwise indicated, specimens are in the United States National Museum.

Alberta. Jasper House, 4'; Shovel Pass, 2'; Jasper Park, 10'; head of Smoky
River, 9; Henry House, 2 (1'); Blindman River, 1'; forks of Blindman River
and Red Deer River, 2 ( 1», 1*); "near Red Deer, Red Deer River", 1'; Red
Deer River, 2 ( 1% 1'); Red Deer, 2'; Rosebud, 2'; Prairie, 3000 ft., 1; Didsbury,
Litde Red Deer River, 1; Canadian Nat'l Park, 1°; Canmore, 1; Banff, 1'; High
River, 1°; "Waterton Lake Park" in Alberta, 6\

British Columbia. Grand Forks of Fraser River, 1; Canoe River, 1'; Field,
1; Glacier, 1'; E side Beaverfoot Range, 4000-4500 ft., 6 mi. SE Fraser Creek,
8'; Wentworth Lake, 1*; Revelstoke, 2 (1', 1'); Spillimach[e]en River, 2';
Sicamous, 2; Albert River, 7000 ft., 1'; Lumby, Creighton Valley, 1'; Okanagan,

4 (2\ V, V); Kettle River Lake, Gold Range, 4000 ft., 1; Crows Nest Station,
1'; Yale District, 3; Fort Hope, 1; Chilliwack Lake, 1'; Skagit, 2 (1', 1');
Skagit Valley, 1'; Skagit Summit, V; Lightning Lakes, 2 mi. N International
Boundary, 3; Osoyoos-Bridesville Summit, 2; Westbridge, V; Rossland, 5';
Creston, mouth Goat Creek, 3'; Yahk, 4\

Idaho. Bonner Co.: Coolin, 4. Benewah County: Benewah, V. Idaho
County: "Pete Kings, Locksa River", 1"; 2 mi. SSE Selway Falls, 1900 ft.,
1"; 4 mi. SW Selway Falls, 5800 ft., 3"; Newsome Cr., 12 mi. above jet. with

5 Fk. Clearwater River, 2'; Iron Mt., to 14 mi. W thereof, 24'; Pilot Cr., % to
2J2 mi. above Newsome Cr., 4'; Sawmill Cr., VA mi. W Newsome, 1'; between
Selway River and S. Fk. Clearwater R., 4'.

Montana. Teton County (of old arrangement of counties): Many Glacier,
4900 ft., 1'; Duck Lake, 6 mi. NE St. Marys Lake, 1; St. Marys, Glacier Park,
1''; Lower St. Marys Lake, 1'. Flathead County: Stanton Lake, 5. County in
question: Bitter Root Mts., 1. Ravalli County: Tin Cup District, 1'; Bass
Creek, 6800 ft., NW of Stevensville, 1; Capitan Peak, 7000 ft., 1; Darby, 2';
Girds Creek, 1'; Charlos Heights, 2'.

Washington. Whatcom County: Twin Lakes, Winchester Mts., 3 (1");
ChiUiwack River, 2600 ft., 2; Cooper Creek, near head, 4500 ft., Hannegan
Pass, 1; Cooper Cr., 4300 ft., Hannegan Pass, 1"; Beaver Creek (2500 ft., and
at McMillan Ranch, 1700 ft.), 2; Barron, Bonite Mine, 5000 ft., 1. Okanogan
County: Tungsten Mine, 6800 ft., Bauerman Ridge, 4; Hidden Lakes, 4100 ft.,
1; West Fork Pasayter River, 4700 ft., 1. Stevens County: Orin, 1". Fend
Oreille County: lone, 2". Chelan County: Lake Chelan, 1".

Mustela erminea alascensis (Merriam)

Ermine

Plates 2, 3, 4, 9, 10 and 11

Putorius richardsoni alascensis Merriam, N. Amer. Fauna, 11:12, pi. 2,
figs. 2, 2a, June 30, 1896.

Putorius cicognanii alascensis, Miller, U. S. Nat. Mus. Bull., 79:96, Decem-
ber 31, 1912; Swarth, Univ. California Publ. Zool., 7:140, January 12,
1911.

Mustela erminea alascensis. Hall, Proc. Biol. Soc. Washington, 57:36, June
28, 1944; Hall, Joum. Mamm., 26:180, July 19, 1945.

1. Canadian National Museum 9. Univ. Washington Museum of Zoology

2. American Mus. Nat. History 10. Collection of William T. Shaw

3. Field Museum of Natural History 11. University of Idaho

4. Museum of Comparative Zoology 12. California Academy of Sciences

5. Royal Ontario Museum of Zoology 13. Museum of Zoology, Univ. Michigan

6. Cornell University 14. Charles R. Conner Museum

7. Mus. Vert. Zool., Univ. California 15. Collection of Walter W. Dalquest

8. Collection of Kenneth Racey 16. Collection of Stanley G. Jevvfett

132 University of Kansas Publs., Mus. Nat. Hist.

Type. — Male, adult, skull and skin; no. 74423, U. S. Nat. Mus., Biol. Surv.
Coll.; Juneau, Alaska; August 22, 1895; obtained by Clark P. Streator, original
no. 4806.

The skull shows malformation of the frontal sinuses due to parasites and
lacks osseous tissue where the parasitic infestation was localized. The left
exoccipital condyle and adjacent region is less developed than the right and
the posterior part of the skull is bent slightly to the left. Otherwise the skull
is unbroken. The teeth all are present and entire. The skin is in the brown
summer coat, fairly well made and in a good state of preservation. A few
white hairs persist where the proximal line of the black hair of the tip of the
tail meets the distal line of the brown hair.

Range. — Mainland of southeastern Alaska from Lynn Canal south to include
Mitkof, Zarembo, Wrangel and Revillagigedo islands. See figures 25, 26 on
pages 95 and 134.

Characters for ready recognition. — Differs from M. e. arctica and haidarum,
in both sexes, by proximal two-thirds of under side of tail colored same as
upper parts rather than same as underparts and interorbital breadth less, in-
stead of more, than distance between glenoid fossa and posterior border of
external auditory meatus; from A/, e. salva, in males, by overall depth of brain-
case including tympanic bullae less than 89 per cent of orbitonasal length, fe-
males not individually distinguishable but averaging shallower through the
braincase; from M. e. initis, celenda and seclusa by interorbital breadth less
than distance between glenoid fossa and posterior border of external auditory
meatus (females of initis, celenda and seclusa unknown); further from initis
by total length less than 317 and black tip of tail less than 57 per cent of length
of tail-vertebrae; further from celenda by chest white, not mostly covered by
brown patch.

Description. — Size. — Male: Eight adults from Windham, Alaska, yield aver-
age and extreme measurements as follows: Total length, 298 (288—315);
length of tail, 88 (84-94); length of hind foot, 41.3 (37-44).

Female: Two adults from Juneau and Helm Bay measure, respectively, as

follows: Total length, 258, 258; length of tail, , 76; length of hind foot,

32, 34.

Color. — As described in Mustela crminea richardsonii except that least
width of color of underparts averaging, in five females, 42 (35-53) per cent
of greatest width of color of upper parts. Black tip of tail in same specimens
averaging 36 (30-40) mm. which is 49 (48-53) per cent of length of tail-
vertebrae.

Skull. — Male ( based on 8 adults from Windham ) : See measurements and
plates, 2-4. As described in Mustela erminea ricliardsonii except that: Weight,
1.8 (1.5-2.6) grams; basilar length, 37.5 (36.5-38.9); length of tooth-rows
more or less than (about same as) length of tympanic bulla.

Female (based on 5 adults, from locafities listed in the table of cranial
measurements): See measurements and plates 9-11. As described in Mus-
tela erminea richardsonii except that: Weight, 0.96 (0.7-1.1) grams; basilar
length, 32.7 (31.9-33.2); breadth of rostrum more or less than (about equal
to) 30 per cent of basilar length.

From richardsonii, alascensis differs in that the skull of the male
averages smaller in every measurement taken and is 28 per cent

MUSTELA ERMINEA 133

lighter. Relative to the basilar length, the orbitonasal length is
more and the braincase is shallower as measured at the anterior
end of the basioccipital. The four adult females seen of alascensis
are more variable than those of richardsonii and average smaller
in some measurements and larger in others but give no proof of
any consistent difference.

From haidarum, alascensis differs in that the rostrum and entire
preorbital part of the skull is actually as well as relatively much
smaller in both sexes. In males of alascensis the length of the
skull, and other cranial measurements of length, is more. In males,
the mastoid breadth and zygomatic breadth are about the same
as in haidarum^, as also is the weight. Ml is larger but ml and
P4 are smaller. In females the anteroposterior extent of the inner
moiety of Ml and length of tympanic bulla are about the same in
the two subspecies but all other cranial and dental measurements
in alascensis are less. It is 29 per cent lighter. The difference
in the preorbital region is of about the same degree as in the males.

Comparisons of the skuU with those of arctica, salva, initis, ce-
lenda, and seclusa are made in the accounts of those subspecies.

Remarks. — The relatively few specimens known of this race
seem always to have been referred to in the literature by the
name alascensis and the nomenclatural history is therefore simple.
The original materials were obtained by the collector Clark P.
Streator and the additional series of skeletons, one with skin, from
Windham were procured by Stanton Price, a resident there.

The subspecies is well differentiated from both arctica and rich-
ardsonii. Although actual intergrades are lacking between alas-
censis and the two races just mentioned I have no doubt that
intergradation occurs with richardsonii and think it probably does
also with arctica.

The assignment of the three females from Mitkof Island,
Zarembo Island, and Loring on Revillagigedo Island, is tentative
because each is so young as not to show diagnostic cranial charac-
ters. The two other specimens from Revillagigedo Island (Carroll
Inlet), labeled as males, are in white winter pelage. Only one,
no. 136358, a subadult, is accompanied by a skull. The small
size of each specimen, and its cranial characters which are inter-
mediate between those of males and females of alascensis of the
adjacent mainland, indicate the existence of a distinct race of
weasel on Revillagigedo Island. On the chance that the one
specimen with a skull is a dwarf, or is wrongly sexed as seems
improbable, the population is tentatively referred to alascensis.

134 University of Kansas Publs., Mus. Nat. Hist.

:" = ": = g

I ::::::_j

? I

specimens
• examined 3

M.e.arctica 4

M. e . richardsonii

JM.e. olascensis 5

^m

M. e.inifis

M. e.salva 6 k-:-:':":":-:-:-! M . e . relgnda

7 iililiiliij M. e .seclusa

Fig. 26. Map showing known occurrences and probable geographic ranges of
the subspecies of Mustela erminea in southeastern Alaska.

MUSTELA ERMINEA 135

Specimens examined. — Total number, 24, arranged by localities from north
to south. Unless otherwise indicated, specimens are in the Museum of Verte-
brate Zoology, University of California.

Alaska. Juneau, 5'; Talcu River, 1; Windham, 9; Mitkof Island, 1; St. John
Harbor, Zarembo Island, 1; Wrangel, 1'; Helm Bay, Cleveland Peninsula, 1;
Cleveland Peninsula, 2'; Revillagigedo Island, Carroll Inlet, 2'; Loring, 1'.

Mustela erminea salva Hall

Ennine

Plates 2, 3, 4, 9, 10 and 11

Mustela erminea salva Hall, Proc. Biol. Soc. Washington, 57:35, June 28,
1944; Hall, Joum. Mamm., 26:180, July 19, 1945.

Type. — Male, adult, skull only; no. 74641, Mus. Vert. Zool.; Mole Harbor,
Admiralty Island, Alaska, December 27, 1936; obtained by A. Hasselborg.

The skull (plates 2-4) shoM^s malformation of the frontal sinuses owing to
parasites and lacks osseous tissue where the parasitic infestation was localized.
The skull is unbroken. The teeth all are present and entire.

Range. — Admiralty Island, Alaska. See figures 25, 26 on pages 95, 134.

Characters for ready recognition (known only from skulls). — Differs from
males of M. e. alascensis in overall depth of braincase which is more than 89
per cent of orbitonasal length; from M. e. initis, in males, in that orbitonasal
length and mastoid breadth total less than 35 mm., weight of skull and lower
jaws less than 2.1 grams; from M. e. celenda, in males, in that breadth of
rostrvun measured across lacrimal processes less than a third of basilar length.

Description- — Size. — Male: An adult from Gambier Bay measures: Total
length, 320; length of tail, 95; length of hind foot, 45 (41 in dry skin).

Female: A subadult from Hawk Inlet, measures: Total length, 250; length
of tail, 70; length of hind foot, 33.

Color. — As described in Mustela erminea richardsonii except that least width
of color of underparts in four individuals 40 (38-43) per cent of greatest
width of color of upper parts. Black tip of tail, in two individuals for which
external measurements are given, amounting to 50 and 40 mm. respectively
which is 53 and 57 per cent of length of tail-vertebrae.

Skull. — Male (type and 4 adult topotypes): See measurements and plates
2-4. As described in Mustela erminea richardsonii except that: Weight, 1.7
(1.5-1.9) grams; basilar length, 37.8 (36.4-39.5, extremes are in subadults);
length of tooth-rows more or less (usually more) than length of tympanic
bulla; interorbital breadth rarely more than distance between glenoid fossa and
posterior border of external auditory meatus.

Female (2 ad. and 1 ad.-sad. topotypes): See measurements, and plates
9-11. As described in Mustela erminea richardsonii except that: Weight,
0.9 (0.8-1.0) grams; basilar length, 33.0 (32.0-33.6); length of tooth rows
approximately same as length of tympanic bulla; breadth of rostrum approxi-
mately 30 per cent of basilar length.

From alascensis, salva differs in that males have the preorbital
region slightly wider in relation to the length of the tympanic bulla;

1. United States National Museum.

136 University of Kansas Publs., Mus. Nat. Hist.

also the braincase is smaller, actually as well as in comparison with
the preorbital part of the skull. The tympanic bullae do not project
so far below the squamosals and the braincase itself is shallower,
in adults averaging only 11.5 mm. as against 12.5 mm. The overall
depth of the braincase, including the tympanic bullae, when divided
into the orbitonasal length gives an average of 93 ( 90-97 ) per cent
whereas in alascensis the figure is only 85 (78-88) per cent. On
this basis alone, everyone of the adult skulls of the two races can
be distinguished. The females and subadult males show the same
tendency to reduction in depth of braincase but not every individual
among them can be surely distinguished. By weight the skull of
salva of corresponding sex is only about 6 per cent smaller. Com-
parisons with initis and celenda are made in the accounts of those
subspecies.

Remarks. — Most of the specimens seen were collected by Allen E.
Hasselborg, resident on Admiralty Island. On the basis of skulls-
few skins, and measurements taken in the flesh, are available — saloa
more closely resembles alascensis than does any other subspecies
so far known from southeastern Alaska. The race on Admiralty
Island is only slightly differentiated from alascensis of the adjacent
mainland.

Specimens examined. — Total number, 26, all from Admiralty Island, Alaska,
arranged in general by localities from north to south, and unless otherwise
indicated in the Museum of Vertebrate Zoology, University of California.

Alaska. Admiralty Island: Hawk Inlet, 2; Seymour Canal, 4; Mole Harbor,
18 (skulls only); Gambier Bay, 1; no locality more definite than Admiralty
Island, 4 (1 in U. S. Nat. Mus.).

Mustela erminea initis Hall

Ermine

Plates 4, 5 and 6

Mustela erminea initis Hall, Proc. Biol. Soc. Washington, 57:37, June 28,
1944; Hall, Joum. Mamm., 26:180, July 19, 1945.

Type. — Male, adult, skull and skin; no. 289, Mus. Vert. Zool.; Saook Bay,
Baranof Island, Alaska; October 9, 1907; obtained by A. Hasselborg, original
no. 4.

The top of the skull is fractured on the left side from the anterior nares
posteriorly through the postorbital process to the posterior root of the
zygomatic arch. On the left lower jaw the canine and three incisors are
missing; otherwise tlie teeth all are present and entire.

The skin is in process of molt, approximately nine-tenths of the incoming
white pelage being in place. The skin is well made and in a good state of
preservation.

Range. — Chichagof and Baranof islands, Alaska. See figures 25, 26 on
pages 95, 134.

MUSTELA ERMINEA 137

Characters for ready recognition (only males known). — Differs from M.
e. arctica, in that proximal two-thirds of under side of tail colored same as
upper parts rather than same as underparts, zygomatic breadth less than
distance between last upper molar and jugular foramen; from M. e. salva in
that orbitonasal length and mastoid breadth total more than 35 mm., weight
of skull and lower jaws more than 2.1 grams; from M. e. alascensis, by total
length more than 317, black tip of tail more than 57 per cent of length of
tail-vertebrae, interorbital breadth more than 10.3 and equal to, instead of
less than, distance between glenoid fossa and posterior border of external
auditory meatus; from M. e. celenda by chest white (not mostly covered
by brown patch), breadth of rostrum measured across lacrimal processes
less than a third of basilar length; from M. e. seclusa in zygomatic breadth
more than distance between last upper molar and jugular foramen.

Description. — Size. — Male: The type and an adult topotype measure,
respectively, as follows: Total length, 330, 320; length of tail, 95, 95; length
of hind foot, 45, 45.

Female: No external measurements available.

Color — As described in Mustela erminea richardsonii except that least width
of color of underparts averages, in two young female topotypes, 50 (49, 50)
per cent of greatest width of color of upper parts. Black tip of tail in three
young female topotypes averaging 54 ( 52-55 ) mm. which is 67 ( 63-69 ) per
cent of length of tail-vertebrae.

Skull. — Male ( illustrated by type and 1 ad. topotype ) : See measurements
and plates 4-6. As described in Mustela erminea richardsonii except that:
Weight, 2.3 and 2.5 grams; basilar length, 39.6, and 40.5; interorbital breadth
equal to distance between glenoid fossa and posterior border of external
auditory meatus.

Female: No adults available.

From salva, initis differs in that skulls of males average larger in
every measurement taken, being 41 per cent heavier. Relative to
the basilar length, the interorbital and preorbital parts of the skull
are larger; the relatively greater interorbital and mastoid breadths
are particularly noticeable. Although the depth of the braincase,
including the tympanic bullae, is both relatively as well as actually
more than in salva, the depth is relatively less than in alascensis
which otherwise differs from initis in about the same way that salva
differs from initis. Whereas the interorbital breadth in initis is about
equal to the distance between the glenoid fossa and the posterior
border of the external auditory meatus, the interorbital breadth is
uniformly less than this distance in both salva and alascensis. In
comparison with seclusa the teeth are of the same size but all
measurements of the skull are larger. The skull of initis is 25 per
cent heavier. In relation to the basilar length, the interorbital and
preorbital parts of the skull are much less in initis. The preorbital
and interorbital regions in initis are relatively smaller in comparison

138 University of Kansas Publs., Mus. Nat. Hist.

also with arctica. The one measurement of interorbital breadth in
initis is greater in relation to the basilar length than in kadiacensis
but the rostral region, and all that part of the skull anterior to the
braincase, is relatively smaller in initis.

Remarks. — The two adult males, nos. 286 and 289 from Saook
Bay, provide convincing evidence of the existence of a distinct race
of weasel on Baranof Island. Three other young specimens, almost
subadult, from the same place are labeled as males although the
basilar lengths of these skulls are only 35.5, 35.9 and 37.3 milh-
meters as against 39.6 and 40.5 in the two adult males. The dif-
ference in size is too great to be age-variation. The fact that 3 are
definitely of one category and 2 of the other makes it doubtful that
individual variation accounts for the differences. The small size of
these 3 specimens and the fact that in each the anterior margin of
the tympanic bulla is flush with the squamosal rather than pro-
truded from the braincase, suggests that the three are females. If
they are females, the amount of secondary sexual variation is rather
less than would be expected by analogy with the amount obtaining
in alascensis on the mainland and in salva on Admiralty Island.
Another possibility that I can not disprove is that two stocks of
weasels persist on Baranof Island, the two larger specimens being
descendants of the stock which first became established on the is-
land and the three smaller specimens being descendants of an indi-
vidual ermine, or of ermines, that were rafted or otherwise trans-
ported to the island at a considerably later date. Assuming for the
moment that there are two stocks, it must be admitted that each
one differs from any stock known from elsewhere. Therefore, each
stock would be presumed to have been long resident on the island.
But — two stocks as closely related as the two in question would not
be expected to persist for long in an area as small as that of Baranof
Island because competition would give one the ascendency. There-
fore, the first suggestion, namely that the three smaller animals are
really females, seems the more probable. The feasible way to clear
up the present uncertainty is, of course, to obtain additional speci-
mens, carefully labeled as to sex. Yet another reason why addi-
tional collecting is desirable in this area is to ascertain whether there
is subspecific differentiation between the ermines of Baranof and
Chichagof islands. The one specimen available from the latter
island, although in general like the three smaller animals from
Baranof Island, differs in the fuller (less scooped out) medial side
of the tympanic bulla and to a slight degree in each of some other

MUSTELA EKMINEA 139

features. This specimen from Chichagof Island is labeled as a male

also.

Specimeris examined. — Total number, 6, arranged by localities from north
to south, and in the Museum of Vertebrate Zoology, University of California.

Alaska. Chichagof Island, Freshwater Bay, 1. Baranof Island, Saook Bay, 5.

Mustela erminea celenda Hall

Ermine

Plates 5, 6 and 7

Mustela erminea celenda Hall, Proc. Biol. Soc. Washington, 57:38, June
28, 1944; Hall, Joum. Mamm., 26:181, July 19, 1945.

Type. — Male, adult, skull and skin; no. 130987, U. S. Nat. Mus., Biol.
Surv'. Coll.; Kasaan Bay, Prince of Wales Island, Alaska; June 16, 1903;
obtained by Cyrus Catt; original no. 4407X.

The skull has a piece 1.5 mm. long broken out of the left zygomatic
arch. P2 is absent on both sides. The right II, and the left II and 12
are missing. The skin, in summer pelage, is fairly well-made. A scrotal
pouch attests to the correctness of the sex recorded on the label. The rostral
part of the skull is smaller than in average-sized males of corresponding age.

Range. — Prince of Wales, Dall, and Long islands, Alaska. See figures
25, 26 on pages 95, 134.

Characters for ready recognition (only males known). — Differs from M.
e. alascensis and initis in chest mostly covered by brown patch, not white,
and breadth of rostrum measured across lacrimal processes more than a tliird
of basilar length, which cranial character serves to distinguish also salva;
from M. e. seclusa in zygomatic breadth less than distance between last upper
molar and jugular foramen; from M. e. haidarum in chest white (not mostly
covered by brown patch), proximal two-thirds of underside of tail colored
Uke upper parts ratlier than underparts, basilar length more than 38.2 mm.

Description. — Size. — Male: Seven adults and subadults from Prince of
Wales Island, yield average and extreme measurements as follows: Total
length, 286 (277-304); length of tail, 77 (74-85); length of hind foot, 36
(35.5-40.5).

Female: No specimen available.

Color. — As described in Mustela erminea richardsonii except that upper
parts about tone 3 of dark Chocolate Brown of Oberthiir and Dauthenay,
pi. 342; lower throat and chest covered by a large patch of same color as
upper parts; color of iinderparts extending to toes but in interrupted fashion
on both fore- and hind-feet; least width of color of underparts averaging, in
four males from Prince of Wales Island, 41 (38-49) per cent of greatest
width of color of upper parts. Black tip of tail averaging, in 8 males in
vmiter pelage, 65 (59-78) mm. which is 84 (69-92) per cent of length of
tail-vertebrae.

From its geographic neighbors alascensis and initis, celenda differs in
darker color of upper parts, presence rather than absence of patch of dark
color on lower throat and chest, and longer black tip on tail. From haidarum,
celenda differs in darker color of upper parts, presence rather than absence

140 University of Kansas Publs., Mus. Nat. Hist.

of patch of dark color on lower throat and chest, narrower hght-colored under
parts, black tip of tail averaging less rather than more than nine-tenths of
length of tail-vertebrae and ventral face of tail colored like upper parts rather
than Uke underparts.

Skull. — Male (illustrated by 5 adults): See measurements and plates 5-7.
As described in Mustela erminea richardsonii except that: Weight, 2.3 (2.2-
2.5) grams; basilar length, 39.5 (38.9-40.7) mm.; length of tooth-rows more
than length of tympanic bulla; breadth of rostrum measured across lacrimal
processes more than a third of basilar length; interorbital breadth more than
distance between glenoid fossa and posterior border of external auditory
meatus; zygomatic breadth more or less than (about equal to) distance be-
tween last upper molar and jugular foramen.

Female. — Complete skull of adult unavailable.

Differences from richardsonii are indicated in the formal de-
scription just given. Additional to differences therein noted, celenda
differs from initis in larger interorbital and preorbital parts of the
skull although dimensions of other parts of the skull and the teeth
are about the same or even less. From salva, celenda differs in
larger average size in every measurement taken, except for the
inner moiety of Ml which is about the same. The skull of celenda
is 35 per cent heavier. In relation to the basilar length the skull
of celenda is wider, especially in the interorbital and preorbital
regions. In comparison with alascensis the tympanic bullae are
of approximately the same length; otherwise essentially the same
differences obtain as are noted in comparison with salva and the
zygomatic breadth is relatively more in celenda. From seclusa, in
which the teeth are of comparable size, celenda differs in that
every cranial measurement is more and the skull is 28 per cent
heavier. Because the skull of celenda is so much longer, its dimen-
sions in other planes are less in relation to the length than in
seclusa. M. e. celenda is larger in every part measured than
haidarum, 21 per cent heavier, and in relation to the basilar
length the interorbital, and preorbital, parts of the skull are smaller,
the braincase is shallower, and the skull is relatively wider across
the zygomata and mastoid processes. In comparison with kadia-
censis, differences are: 26 per cent lighter, skull shorter; in re-
lation to the basilar length, braincase shallower as measured at
the anterior end of the basioccipital, tooth-rows shorter but orbi-
tonasal length more. In comparison with arctica all parts measured
of the teeth and skull of celenda are smaller and its skull is 34
per cent lighter. In relation to the basilar length, the interorbital
breadth of celenda is only slightly less but its skull is narrower

MUSTELA ERMINEA 141

across the rostrum and zygomata, the tooth-rows are shorter, and
the braincase is shallower.

Remarks. — The late George Willett in the course of his work in
Alaska collected most of the known specimens of this strongly
differentiated subspecies. In both coloration and cranial characters
the distinguishing features are so well marked that the zoologist
could with reason accord full specific rank to celenda. Neverthe-
less it obviously is an ermine. Also, races from other islands of
southeastern Alaska tend to bridge the gap, as regards cranial
features, between celenda and the mainland ermine. The specimen
from Dall Island agrees in all respects with topotypes. The speci-
men from Howkan on Long Island is in white winter pelage and
the skull has suffered shrinkage from some chemical solution; the
reference of this specimen to celenda is tentative.

Specimens examined. — Total number, 25, as follows: Arranged by locali-
ties from north to south. Unless otherwise indicated, in U. S. National
Museum.

Alaska. Prince of Wales Island: Craig, 18 (10 in Mus. Vert. Zool., and 8 in
Los Angeles Mus. Hist. Art and Sci. ) ; Kasaan Bay, 2; no locality more def-
inite than the Island itself, 3; Dall Island, Otter Harbor, 1 (Los Angeles Mus.
Hist. Art and Sci.). Long Island, Howkan, 1 (Field Mus. Nat. Hist.).

Mustela erminea seclusa Hall

Ermine

Plates 5, 6 and 7

Mustela erminea seclusa Hall, Proc. Biol. Soc. Washington, 57:39, June
28, 1944; Hall, Joum. Mamm., 26:181, July 19, 1945.

Type. — Male, adult, skull alone; no. 31232, Mus. Vert. Zool.; Port Santa
Cruz, Suemez Island, Alaska; March 24, 1920; obtained by George Willett.

The skull (plates 5-7) is complete and unbroken. Of tlie upper incisors
only right 13 is present. Otherwise the teeth are present and unbroken.

Range. — Known only from the type locality. See figures 25, 26 on pages
95, 134.

Characters for ready recognition (only the male known). — DiflFers from
M. e. celenda in basilar length less than 38.2, from M. e. salva, initis and
haidarum in zygomatic breadth more than distance between last upper molar
and jugular foramen.

Description. — Size and Color. — No external measurements or skins available.

Skull. — Male: See measurements and plates 5-7. As described in Mustela
erminea richardsonii except that: Weight, 1.8 grams; basilar length, 34.3;
length of tooth-rows about the same as length of tympanic bulla; breadth
of rostrum measured across lacrimal processes more than a third of basilar
length; interorbital breadth more tlian distance between glenoid fossa and
posterior margin of external auditory meatus; z\'gomatic breadth more than
distance between last upper molar and jugular foramen.

Female. — Skull not available.

142 University of Kansas Publs., Mus. Nat. Hist.

From alascensis and salva, seclusa differs in larger teeth, shorter
skull, much larger preorbital and interorbital regions, actually as
well as in relation to basilar length. Excepting the teeth, which
are of about the same size, the same general differences obtain in
comparison with initis which, however, is 29 per cent heavier.

From celenda, seclusa differs in smaller skull in all parts measured,
being 22 per cent lighter. The teeth are about the same size. In
relation to its length the skull of seclusa is much broader and deeper.
From haidarum, seclusa differs in: teeth larger; skull shorter and
more convex in dorsal outline along median longitudinal axis;
in relation to basilar length, skull broader, deeper and braincase
relatively shorter.

Remarks. — The characters shown in the one available skull are
far outside the limits of individual variation for other known sub-
species. Other specimens are much to be desired to ascertain what
the "average" individual is like and to learn the characters of the
female.

Specimen examined. — One, the holotype.

Mustela erminea haidarum (Preble)
Ermine
Plates 5, 6, 7, 11, 12 and 13

Putorius haidnrum Preble, Proc. Biol. Soc. Washington, 12:169, August

10, 1898.
Mustela haidarum, Miller, U. S. Nat. Mus. Bull., 79:97, December 31,

1912.
Mustela erminea haidarum. Hall, Proc. Biol. Soc. Washington, 57:38, June

28, 1944; Hall, Joum. Mamm., 26:181, July 19, 1945.

Type. — Male, adult, skull, skeleton and skin; no. 94430, U. S. Nat. Mus.,
Biol. Surv. Coll.; Massett, Queen Charlotte Islands, British Columbia; March
17, 1898; obtained by J. H. Keen; original no. 1800x.

The skull is unbroken and complete except for osseous tissue destroyed
in the region of each postorbital process; this is the result of infestation of
the frontal sinuses by parasites. The skeleton is complete down to the distal
ends of the tibiae; the more distal bones are in the skin. The first, right,
upper incisor is missing. Otherwise the teeth all are present and entire.

The skin is in the white, winter pelage but the new under fur is visible
along the back and on the head although mostly covered with white hair.

Range. — Queen Charlotte Islands. See figure 25, page 95.

Characters for ready recognition. — DifiFers from M. e. celenda in chest
white (not mostly covered by brown patch), proximal two-thirds of under
side of tail colored Uke underparts instead of upper parts, in males basilar
length less than 38.2; from M. e. seclusa, in male, in zygomatic breadtli
less than distance between last upper molar and jugular foramen; from M. e.
richardsonii and alascensis, in both sexes, in proximal two-thirds of under

MUSTELA ERMINEA 143

side of tail colored like underparts instead of upper parts, interorbital breadth
not less than distance from glenoid fossa to posterior margin of external
auditory meatus; from M. e. anguinae and fallenda, in both sexes, in light-
colored underparts more than half the width of dark-colored upper parts,
proximal two-thirds of under surface of tail colored like underparts instead
of upper parts, interorbital breadth equal to or more than distance between
glenoid fossa and posterior margin of external auditory meatus.

Description. — Size. — Male: Two adults, U. S. N. M., no. 100622, from
Cumsheva Inlet, and Amer. Mus. N. H., no. 37411, and the type, measure,
respectively, as follows: Total length, 283, 290, 275; length of tail, 70, 75,
60; length of hind foot, 39, 40, 37.

Female: Corresponding measurements of an adult, no. 100624, and a
young individual, no. 100623, each from Cumsheva Inlet, are: 252, 250;
63, 61; 31, 32.

Color. — As described in Mustela erminea richardsonii except that under-
parts not Sulphur Yellow but ranging from near (e) Colonial Buff through
Marguerite Yellow to almost pure white; color of underparts extends distally
on posterior sides of forelegs and onto toes but in many specimens interrupted
at wrist by color of upper parts; color of underparts extends onto proximal
three-fourths of under side of tail as length of tail is measured along tail-
vertebrae; least width of color of underparts averaging, in 5 males, 79 (66-130)
per cent of greatest width of color of upper parts. Black tip of tail in same
males averaging 62 (60-70) mm. which is 92 (83-115) per cent of length
of tail-vertebrae.

The close correspondence in color-pattern of this weasel with the Arctic
races, arctica, polaris, semplei and kadiacensis is noteworthy, and distinguishes
it from weasels on the adjacent mainland and adjoining islands to the north
and south. The color of the upper parts is darker than in the four Arctic
races named.

Skull. — Male ( 7 adults ) : See measurements and plates 5-7. As described
in Mustela erminea richardsonii except that: Weight, 1.9 (1.7-2.0) grams;
basilar length, 36.7 (35.6-37.5); length of tooth-rows more than length of
tympanic bullae; breadth of rostrum measured across lacrimal processes
more than a third of basilar length; interorbital breadth more than distance
between glenoid fossa and posterior margin of external auditory meatus;
zygomatic breadth barely less than distance between last upper molar and
jugular foramen.

Female (2 adults): See measurements and plates 11-13. As described
in Mustela erminea ricliardsonii except that: Weight, 1.3 and 1.4 grams;
basilar length, 34.2; length of tooth-rows more or less than (about equal to)
length of tympanic bulla; breadth of rostrum more than 30 per cent of basilar
length; interorbital breadth not less than distance between glenoid fossa and
posterior margin of external auditory meatus.

From richardsonii, haidarum differs in that skull of the male is
actually larger in its anterior part (breadth of rostrum, interorbital
breadth and orbitonasal length ) but all measurements of other parts
average less. In relation to the basilar length, the tympanic bulla is
shorter but all other measurements are more. In the skull of the fe-

144 University of Kansas Publs., Mus. Nat. Hist.

male, which is 23 per cent heavier, the v^idth of the tympanic bulla
and anteroposterior extent of the inner lobe of Ml are the same; in
all other measurements the female of haidarum is larger, and in
relation to the basilar length all measurements are more except the
depth of the skull at the anterior margin of the basioccipital and
the width of the tympanic bulla, which are less. By actual weight
the skull of the male is 25 per cent lighter and the skull of the
female 24 per cent heavier than in richardsonii. From fallenda
and anguinae, haidarum differs in that measurements of the skulls
of both sexes either average more, or are uniformly more, with two
exceptions. These are the lesser length and breadth of the tympanic
bulla, in comparison with males of fallenda, and the dimensions of
Ml which are about the same in all three races concerned. The
pre- and inter-orbital parts are larger in relation to the remainder
of the skull. The postorbital breadth is actually a third more
than in fallenda. In relation to the basilar length, the tympanic
bulla is shorter and the braincase deeper than in males of anguinae.
The skull of the male is 27 per cent heavier than that of fallenda
and 58 per cent heavier than that of anguinae. The skull of the
female is 59 and 50 per cent heavier than those of fallenda and
anguinae, respectively. Comparison of the skull with those of
alascensis, celenda and seclusa has been made in the accounts of
those subspecies.

Remarks. — The available specimens of this ermine were obtained
by J. H. Keen in 1898, Wilfred H. Osgood and E. A. Lewis in 1900,
W. W. Brown in 1914, J. A. Munro in 1917 and 1918, and Allan
Brooks in 1920. M. e. haidarum has more claim to full specific
status than any other race of ermine because the diagnostic
structural features are numerous and individually of relatively
great degree. Indeed, individual variation appears not to bridge
the gap between any population of haidarum and other subspecies
and strong reasons could be advanced for according haidarum the
status of a full species. It differs from the subspecies of erminea
on the adjoining mainland and adjoining islands to the north and
south and agrees with the Arctic races (arctica, polaris, semplei
and kadiacensis) in great extent of the color of the underparts,
extension of this color onto the underneath side of the tail, long
black tip of the tail and general form of the skull including
the relatively heavy preorbital region. The color although darker
than in the Arctic subspecies, is lighter than in the insular races
ifnmediately to the north and south. In combination, the features

MUSTELA ERMINEA 145

mentioned could be taken as indication that haidarum is a relict
population from a former glacial period. Assuming that it is a
relict population, the color may have become slightly darker since
that period but the main response appears to have been a decrease
in size for this is a much smaller animal than the Arctic ermines.
The size is about what would be expected if one were to judge
by the slightly larger ermines on the islands of southeastern Alaska
to the north and the smaller ermine on Vancouver Island to the
south.

The ermines of the islands of southeastern Alaska, excepting
possibly the incompletely known seclusa, have fewer characters
of the Arctic races and more characters of the races of the adjoining
mainland. Therefore, a possible inference is that the distinctive
characters of ermines of the Alaskan islands developed with the aid
of isolation from stocks which reached the islands after the glacial
period. M. e. haidarum may have found its way to the Queen
Charlotte Islands in the glacial period.

Specimens examined. — Total number, 17, as follows. Arranged by locality
from north to south. Unless otlierwise indicated, specimens are in the U. S.
National Museum.

British Columbia. Queen Charlotte Islands. Masset, 7 (4', 1', 1'); Skid-
gate, 1; Graham Island, 5 (2', 1°, 1'); Cumsheva Inlet, 3; no locahty more
definite than Queen Charlotte Islands, V.

Mustela erminea anguinae Hall

Ermine
Plates 5, 6, 7, 11, 12 and 13

Mustela cicognanii anguinae Hall, Univ. CaUfomia Publ. Zool., 38:417,

November 8, 1932.
Puforius cicognanii, Baird, Mamm. N. Amer., p. 161, 1858 (part).
Pulorius streatori, Swarth, Univ. California Publ. Zool., 10:102, February

13, 1912.
Mustela erminea anguinae Hall, Journ. Mamm., 26:79, February 27, 1945;

Hall, Journ. Jvlamm., 26:181, July 19, 1945.

Type. — Male, adult, complete skeleton (no skin); no. 12482, Mus. Vert.
Zool., French Creek, Vancouver Island, British Columbia; found as a des-
iccated carcass on May 1, 1910; obtained by Harry S. Swarth.

Range. — Vancouver Island, British Columbia. See figures 25, 27 pages
95, 149.

Characters for ready recognition. — DifiFers from M. e. haidarum, in
both sexes, in Hght-colored underparts less than half the wddth of dark-colored
upper parts, proximal two-thirds of under surface of tail colored like upper

1. Mus. Vert. Zool., Univ. California 4. Univ. Washington Museum of Zoology

2. American Mus. Nat. History 5. Canadian National Museuem

3. Donald R. Dickey Collection

146 University of Kansas Publs., Mus. Nat. Hist.

parts instead of underparts, interorbital breadth less than distance between
glenoid fossa and posterior margin of external auditory meatus; from M. e.
fallenda, in both sexes, anterior margin of tympanic bullae flush with squa-
mosal rather than projecting from floor of braincase, in males by sagittal
crest absent, in females by total length more than 238 and tooth-rows about
same length as, instead of longer than, tympanic bulla; from M. e. streatori,
in male, by sagittal crest absent and hind foot ordinarily more than 33.5,
in female by hind foot more than 27.5, basilar length more than 30.2; from
M. e. olympica, in males, by greater average size, hind foot ordinarily more
than 33.4 and interorbital breadth ordinarily more than 8.5, in females by
larger size, total length more than 235, tail more than 65, hind foot more than
27.5, basilar length more than 30.2.

Description. — Size. — Male: Sixteen adults and subadults yield average
and extreme measurements as follows: Total length, 272 (261-284) mm.;
length of tail, 81 (74-86); length of hind foot, 35.0 (33.5-36).

Female: Five adults and subadults have corresponding measurements as
follows: 247 (241-257); 69 (66-73); 30.0 (28.0-32.0).

Color. — As described in Mustela erminea streatori except that: occasionally
white in winter; upper parts about tone 2 of Dark Chocolate of Oberthiir and
Dauthenay; least width of color of underparts averaging, in 7 adult males,
6 (0-15) per cent of greatest width of color of upper parts. Black tip of
tail in same series averaging 37 (26-46) mm. which is 46 (32-54) per cent
of length of tail-vertebrae.

Skull. — Male (based on 13 adults): See measurements and plates 5-7.
As described in Mustela erminea richardsonii except that: Weight, 1.2 (1.0-
1.3) grams; basilar length, 34.0 (32.5-35.6); length of tooth-rows more or
less (usually less) than length of tympanic bulla.

Female (based on 5 adults): See measurements and plates 11-13. As
described in Mustela erminea richardsonii except that: Weight 0.9 (0.77-
1.06) grams; basilar length, 31.5 (30.9-31.8) grams; length of tooth-rows
more or less than (approximately same as) length of tympanic bulla; breadth
of rostrum more than 30 per cent of basilar length.

The sexual dimorphism in the skull is slight, the skull of the
male being only a third heavier than that of the female. In fal-
lenda of the adjacent mainland to the east the male is three-
fourths heavier than the female. In comparison with fallenda,
males are smaller, averaging less in every cranial and dental
measurement taken and by weight are a fifth lighter; sagittal
crest absent rather than present; tympanic bullae flush with squa-
mosal rather than projecting below floor of braincase; in relation
to basilar length, tympanic bullae smaller, braincase deeper and
broader, skull wider interorbitally and across zygomata. Females
are larger than in fallenda, and with one exception average larger
in every cranial and dental measurement taken, being 6 per cent
heavier. The one exception mentioned is the lesser actual length
of the tympanic bulla in anguinae, in which the length of the tooth-

J

MUSTELA ERMINEA 147

rows is about the same as, rather than less than, the length of
the tympanic bulla. The postorbital breadth is greater than in
fallenda and the anterior edges of the tympanic bullae are flush
with the squamosals rather than projecting below the floor of brain-
case. In relation to the skull as a whole the preorbital and in-
terorbital parts are larger.

In comparison with streatori, skulls of males are of about the
same size, anguinae being only 9 per cent heavier. The length of
the tooth-rows is ordinarily less than, rather than about equal to,
the length of the tympanic bulla; sagittal crest wanting rather than
present since in anguinae the temporal muscles meet usually only
at the posterior end of the braincase instead of all along the mid-
line on its top; tympanic bullae narrower and more nearly flush
with squamosal (less protruded from braincase). Relative to the
basilar length, the zygomatic breadth is more, the tympanic bullae
are narrower, and the braincase is deeper at the anterior end of
the basioccipital. The female is 41 per cent heavier than streatori,
there being no overlap in most cranial and dental measurements.
Ml, however, is approximately the same size in each subspecies.
The tooth-rows and tympanic bulla are of almost equal length
whereas in streatori the length of the tooth-rows is less than that
of the bulla.

Difterences from olympica, in males, are: Ml shorter; all other
measurements of teeth and parts of skull averaging larger; skull
20 per cent heavier; tooth-rows averaging shorter than tympanic
bulla rather than about the same; relative to basilar length, brain-
case deeper at anterior end of basioccipital and tooth-rows shorter.
The skull of the female is 64 per cent heavier, larger in every
measurement taken without overlap; temporal ridges meeting,
rather than separated, at lambdoidal crest; length of tooth-rows
about equal to, rather than shorter than, tympanic bulla; in re-
lation to basilar length, skull deeper, orbitonasal length more,
mastoid and zygomatic breadths more, and tympanic bullae shorter.

Remarks. — References in the literature to this insular race mostly
were under the name streatori until 1932 when in the course of the
present study the name anguinae was proposed. A few specimens
have been taken by nearly every student of small mammals who
has collected on Vancouver Island. Arthur Peake and Herbert
Laing have probably collected more specimens than any other
two zoologists.

M. c. anguinae is noteworthy for the slight secondary sexual

148 University of Kansas Publs., Mus. Nat, Hist.

variation in size; the disparity between the two sexes is less than
in any other American subspecies of erminea. By hnear measure-
ment the body of the female is only 7 per cent shorter than in the
male (178 versus 191 mm.). Linear measurements and weights of
the skulls of the two sexes are further indicative of this approxima-
tion in size. By weight the skull of the female is only a fourth
lighter than that of the male, or, stated in another way, the male's
skuU is only a third heavier (1.2 versus 0.9 grams).

No geographic variation has been detected between lots of
specimens from different parts of Vancouver Island. The one
specimen available from Salt Spring Island presents no obvious
differences from selected individuals from Vancouver Island.

The winter pelage is more often brown than white. Of 17
specimens seen in winter pelage or in transition pelage, only 6
are white. These 6 are from Comox, Stamp River, Hilliers, Jeune
Landing and Port Alice. Of the 34 specimens in brown pelage,
7 have the dark color of the upper parts meeting on the abdomen.
Six of the 34 have brown color on the pectoral region. In two,
this is a separate patch but in the other four the dark color is
a continuation of the upper parts and extends in front of each
foreleg over part of the pectoral region, but the two extensions,
one from either side, do not meet on the underparts. The color
of the lips was recorded in 22 individuals: one had both the upper-
and lower-lips white; 7 had the upper lips brown and the lower
lips white; in 14 both the upper- and lower-Hps were brown.

Specimens examined. — Total number, 40, listed by localities from north

to south as follows. Unless otherwise indicated, specimens are in the National

Musemn of Canada.

British Columbia. Vancouver Island: Cape Scott, 4; Shushartie, 1; Quatsino,
1'; Jeune Landing, 1'; Port Alice, 5'; Marble Creek, Quatsino Sound, 1'; Port
Hardy, 5; Sayward, 2; Bear Lake, 4; Bear River, 1; Comox, 4 (3*); Stamp River,
Albemi, 1°; Errington, 1'; French Creek, 1'; HilUers, 1'; Craigs Crossing,
1'; Nanaimo, 2'; Cowichan Lake, 1'; Duncan, 2\ Salt Spring Island, 1*.

Mustela erminea fallenda Hall

Ermine

Plates 5, 6, 7, 11, 12 and 13

Mustela erminea fallenda Hall, Joum. Mamm., 26:79, February 27, 1945;

Hall, Joum. Mamm., 26:181, July 19, 1945.
Putorius streatori Merriam, N. Amer. Fauna, 11:13, June 30, 1896 (part-

Sumas).

1. Mus. Vert. Zool., Univ. California 4. Provincial Museum of British Columbia

2. Collection of Arthur Peake 5. Collection of Kenneth Racey

3. Collection of J. A. Munro

MUSTELA ERMINEA

149

123

O type locality
M. e, r ic hard son ii

specimens examined

2 tifiiSjiiiild M.e.invicfa
M.e.anquinae
M.e . fallendo

lim^giM

qM

M.e.oly mpi c a
M.e.streaton
M.e .quioso
M.e.mu r I c us

Fig. 27. Map showing known occurrences and probable geographic ranges
of the subspecies of Mustela erminea in Washington and parts of British Colum-
bia and Oregon.

150 University of Kansas Publs., Mus. Nat. Hist.

Type. — Male, adult, skull and skin; no. 7096, Nat. Mus. Canada; Hunting-
don, British Columbia; May 21, 1927; obtained by C. H. Young, original
no. 317.

The brown summer sldn is well made. The skull (plates 5-7) is complete.
Right p2 has the crown broken away; otherwise the teeth all are present
and entire.

Range. — On mainland in immediate vicinity of coast from probably op-
posite Texada Island, British Columbia, south to Lake Whatcom, Washington,
and east to Mount Baker Range on International boundary. See figures 25,
27 on pages 95, 149.

Characters for ready recognition. — DiflFers from M. e. haidarum, in both
sexes, in hght-colored underparts less than half the width of dark-coloroed
upper parts, proximal two-thirds of under surface of tail colored like
upper parts instead of underparts, interorbital breadth less than distance
between glenoid fossa and posterior margin of external auditory meatus;
from M. e. richardsonii in both sexes, by upper hps brown rather than white,
in males hind foot less than 41 and basilar length less than 38.3, in females
hind foot less than 29, basilar length less than 31.4 and breadth of rostrum
more, instead of less, than 30 per cent of basilar length; from M. e. invicta,
in both sexes, by upper lips brown (not white); in males by skull averaging
shorter (basilar length 35.7 versus 37.0); in females by breadth of rostrum
more, instead of less, than 30 per cent of basilar length; from M. e. anguinae,
in both sexes, by anterior margin of tympanic bulla projecting from floor of
braincase rather than flush with squamosal ( the difi^erence is slight in females ) ,
in males by sagittal crest present, in females by total length less than 238 and
tooth -rows longer than, instead of about same length as, tympanic bulla; from
M. e. streatori, in both sexes, by black tip of tail more than half of length
of tail-vertebrae, in males hind foot more than 33.7, tympanic bulla longer
than, instead of about same length as, upper tooth-rows; weight of skull more
than 1/4 grams, in females weight of skull more than 0.7 grams, length of
lateral side of P4, 4 mm. or more; from M . e. olympica, in males, length of
hind foot more than 33, black tip of tail more than 36.5 mm., weight of
skull more than 1.2 grams, basilar length more than 33.5, in females length
of hind foot more than 25.5, weight of skull more than 0.66 grams, basilar
length more than 28.4; from M. e. gulosa, in both sexes, by anterior margin
of tympanic bulla projecting below floor of braincase rather than flush with
squamosal (the difference is slight in females), in males hind foot more than
33.5, weight of skull more than IM grams, basilar length more than 33.9, in
females by total length more than 222, hind foot longer than 26, weight of
skull more than 0.7 grams, basilar length more than 29.

Description. — Size. — Male: Seven adult topotypes yield average and ex-
treme measurements as follows: Total length, 278 (249-305); length of tail,
77 (69-81); length of hind foot, 36.5 (34-40). A male topotype of un-
known age weighed 113 grams.

Female: Two adult topotypes, with actual measurements in parentheses,
average as follows: Total length, 232 (228-236); length of tail, 60 (57-
62); length of hind foot, 27 (27-27). An adult from Morovitz Guard Station,
Wash., weighed 54 grams.

Color. — Winter pelage rarely white, brown pelage indistinguishable from

MUSTELA ERMINEA 151

summer pelage except for slightly more smoky tinge in winter in specimens
from some localities; otherwise as described in Mustela erminea streatori ex-
cept that least width of color of underparts averaging, in seven adult topo-
types, 18 (0-37) per cent of greatest width of color of upper parts. Black
tip of tail averaging, in same series, 45 (38-52) mm. which is 58 (53-65) per
cent of length of tail-vertebrae.

In comparison with richardsonii and invicta, fallenda diflFers in darker
color of upper parts and their extension at the expense of the hght-colored
vmderparts which are narrower by a half. In correlation with this restriction
in area of the light-colored underparts, the upper lips are brown instead of
white. In comparison with anguinae, olympica and streatori, the longer black
tip on the tail is the principal difference in color. From gulosa, fallenda
differs in slightly darker color of upper parts and in narrow underparts, the
width of the same being only about a fifth instead of a third of the width of
the dark-colored upper parts.

Skxdl. — Male ( based on 7 adults ) : See measurements and plates 5-7. As
described in Mustela erminea richardsonii except that: Weight, 1.5 (1.3-
1.7) grams; basilar length, 35.7 (34.3-38.2).

Female (based on 6 ads.): See measurements and plates 11-13. As de-
scribed in Mustela erminea richardsonii except that: Weight, 0.85 (0.73-1.0)
grams; basilar length, 30.6 (29.4-31.7); breadth of rostrum more than 30
per cent of basilar length.

In comparison with richardsonii, skulls of males differ as follows:
averaging smaller in every measurement taken with no overlap in
several dimensions; 40 per cent lighter; in relation to basilar length,
rostrum (orbitonasal length) longer and skull slightly broader in-
terorbitally. Females average smaller in every cranial and dental
measurement taken with no overlap in basilar length, length of
tooth-rows and length of tympanic bulla; 22 per cent lighter;
breadth of rostrum more, rather than less, than 30 per cent of
basilar length; in relation to basilar length, pre- and inter-orbital
parts of skull larger, and mastoid breadth more.

Differences from males of olympica are: size larger with no over-
lap in most measurements; 50 per cent heavier; tympanic bullae
longer than upper tooth-rows rather than of about equal length;
in relation to basilar length, rostrum shorter, braincase wider and
deeper, zygomata more expanded. Females are larger with no
overlap in most measurements; 35 per cent heavier; in relation to
basilar length, pre- and inter-orbital regions narrower, braincase
deeper and wider across mastoids.

Differences from streatori, in males, are: skull averaging larger
in every cranial and dental measurement taken; 36 per cent heavier;
tympanic bulla longer than, instead of about same length as, upper
tooth-rows. In females the inner lobe of Ml is shorter antero-
posteriorly; otherwise all measurements of fallenda average larger

152 University of Kansas Publs., Mus. Nat. Hist.

and it is 33 per cent heavier; rostrum and interorbital region broader
in relation to remainder of skull.

In comparison with gulosa, skulls of males differ as follows:
averaging larger in every measurement taken with no overlap in
several dimensions; 50 per cent heavier; tympanic bullae wdth
anterior margins projecting slightly below squamosals rather than
flush with same; length of bulla more than, rather than about same
as, that of upper tooth-rows. Considering the great difference
in size, the relative proportions are remarkably alike. In females,
length of inner lobe of Ml about the same; otherwise averaging
larger in every measurement taken; 44 per cent lighter; relative
to basilar length, tooth-rows longer, skull wider across zygomata
and mastoids, rostrum and interorbital regions slightly narrower,
skull shallower in plane of last upper molars.

Comparisons with haidariim, invicta and ongui7iae are made in
accounts of those subspecies.

Remarks. — Until the name fallenda was proposed in the course
of the present study, most of the specimens of this race were
assigned to streatori.

Intergradation v/ith streatori is complete as it is also with invicta
and richardsonii, in other words with each of the subspecies whose
ranges meet that of fallenda. In color and in size the difference
is least between streatori and fallenda. As between fallenda and
invicta the size is not greatly different and the intergradation in
color is gradual. Between fallenda and richardsonii intergradation
is somewhat different and to fully appreciate its nature we should
remember that the color of fallenda resembles that of the saturate
coastal races, streatori, anguinae and olympica although the black
tip of the tail is longer. In this latter feature and in several cranial
details, as well as in greater degree of secondary sexual variation
in size, fallenda resembles richardsonii. Because the two differ
more than do most subspecies of ermine whose ranges meet, some
of the intergrades at first inspection appear to be widely different
from either parent stock. For example, specimens from Alta Lake,
British Columbia, may give this impression because the combina-
tion of large size and dark color suggests a kind of ermine different
from either fallenda or richardsonii. In no instance, however, has
there been found in these intergrades any character other than
those occurring in one or the other of the two parent races.

Along the coast in the north part of the geographic range assigned
to fallenda, some specimens nearly typical of richardsonii have
been taken so near to the place where fairly typical fallenda was

MUSTELA ERMINEA 153

obtained that I have doubted whether there is intergradation in
the usual fashion in this area; more specimens will have to be
obtained from this coastal area to resolve the doubt one way or
the other.

The winter pelage is brown in all specimens at most localities.
The only white pelage seen was in each of tliree specimens from
Glacier, Whatcom County, Washington. A fourth specimen from
there is in brown winter pelage. At any one locality there is much
variation in the degree to which the dark color of the upper parts
encroaches on die area that in most other races is light-colored.
An extreme degree of encroachment is shown by a specimen taken
on December 1, 1935, by R. A. Cummings, at Vancouver, British
Columbia, in which the light color occurs only in three restricted
areas, the chin, the throat and the lower breast; otherwise the coat
is brown. There are other specimens, for instance from the type
locality, which differ mainly in having an additional white spot in
the inguinal region. The opposite extreme, in a specimen also from
the tyjDe locality, is where the least width of the light-colored
underparts on the abdominal region is a third of the circumference
of the body. The two extremes are connected by a dozen inter-
mediate stages. Of 64 specimens in which the color of the lips was
carefully examined, one, from Vancouver, has both the upper- and
lower-lips brown; 9 have both the upper- and lower-lips white;
and 54 have the upper lips brown and the lower lips white.

Specimens examined. — Total number, 72, arranged by localities from north
to south. Unless otherwise indicated, specimens are in the National Museum
of Canada.

British Columbia. Horseshoe Lake, Stillwater, 2; Vancouver, 1'; Point Grey,
V; Port Moody, .5^'; ChilUwack, 8 (2', 4% P); Sumas, 19 ( 18\ 1*); Thurstons
Ranch, 2; Cultus Lake, 2; Mt. Baker Range, 5'; Lihumption Park, 1; Hunting-
don, 14; Tami Hy Creek, 1.

Washington, Whatcom Co.: Semiahmoo, 1"; New Whatcom, 1°; Lake
Whatcom, 2'; 5 mi. W Glacier, 1^ Glacier (3 at 900 ft.), 4-'; E Side Easton
Glacier, Mt. Baker, V; Morovitz Guard Station, 831 ft., 1".

Mustela erminea olympica Hall

Ermine

Plates 5, 6, 7, 12, 13 and 14

Mustela erminea olympica Hall, Joum. Mamm., 26:81, February 27, 1945;

Hall, Journ. Mamm., 26:181, July 19, 1945.
Mustela rixosa, Svihla and Svihla, Mmrelet, 13:24, January, 1932.
Mustela rixosa rixosa, Svihla and Svihla, Murrelet, 14:39, May, 1933.

1. Mus. Vert. Zool., Univ. California 5. Lcland Stanford Junior University

2. United States National Museum 6. Collection of William T. Shaw

3. Museum of Comparative Zoology 7. Collection of Kenneth Racey

4. Field Museum of Natural History 8. Collection of Walter W. Dalquest

154 University of Kansas Publs., Mus. Nat. Hist.

Type.— Male, adult, skull and skin; no. 90738, U. S. Nat. Mus., Biol. Surv.
Coll.; near head of Soleduck River, 4500 ft., Olympic Mountains, Clallam
County, Washington; April 28, 1897; obtained by Vernon Bailey, original no.
6213.

The skin is well prepared and in good condition. The skull (plates 5-7)
is unbroken and the teeth all are present and entire.

Range. — Olympic Peninsula, Wasliington, south to Olympia. See figures
25, 27 on pages 95, 149.

Characters for ready recognition. — DiflFers from M. e. anguinae, in males,
by lesser average size, hind foot ordinarily less than 33.4, and interorbital
breadth ordinarily less than 8.5, in females by smaller size, total length less
than 235, tail less than 65, hind foot less than 27.5, basilar length less than
30.2; from M. e. fallenda, in males, by length of hind foot less than 33, black
tip of tail less than 36.5, weight of skull less than 1.2 giams, basilar length less
than 33.5, in females length of hind foot less than 25.5, weight of skull less
than 0.6 grams, basilar length less than 28.4; from M. e. streatori by smaller
size, in males hind foot less than 33.0, basilar length ordinarily less than 32.5,
in females by hind foot ordinarily not longer than 24, by breadth of rostrum
less than 8.6, depth of braincase at posterior border of upper molars less than
7.6.

Description. — Size. — Male: Twelve individuals of adult proportions yield
average and extreme measurements as follows: Total length, 243 (205-269);
length of tail, 65 (60-74); length of hind foot, 31 (29-32).

Female: Corresponding measurements of six females are: 196 (188-208),
52 (45-60?), 23.4 (22.7-24.0). An adult weighs 30 grams.

Color. — As described in Mustela erminea streatori except that least width
of color of underparts averaging, in 12 males of adult proportions, 5 (0-11)
per cent of greatest width of color of upper parts. Black tip of tail averaging,
in same series, 26 (20-35) mm., which is 40 (31-58) per cent (average the
same as in streatori ) of length of tail-vertebrae.

Skull. — Male (based on 5 adults): See measurements and plates 5-7. As
described in Mustela erminea richardsonii except that: Weight, 1.0 (0.9-1.1)
grams; basilar length, 31.8 (30.6-32.5); length of tooth-rows more or less than
( about equal to ) length of tympanic bulla.

Female (illustrated by 3 adults): See measurements and plates 12-14. As
described in Mustela erminea richardsonii except that: Weight, 0.55 (0.52-
0.58) grams; basilar length, 27.1 (26.7-27.5); breadth of rostrum more than
30 per cent of basilar length.

In comparison with streatori, skulls of corresponding sex average
smaller in every measurement taken with no overlap in most of
those of females. Exception is to be made for the inner lobe of
Ml in males where the size is the same. By weight males are
smaller by 10 per cent and females by 14 per cent. In relation to
other parts of the skull the tympanic bullae are narrower and in fe-
males they are shorter as well. Comparison with anguinae and fal-
lenda has been made in the accounts of those subspecies.

MUSTELA ERMINEA 155

Remarks. — The smaller size, especially of females, is the principal
feature distinguishing this race from streatori. On the basis of
available data the female of olympica is smaller than that of any
other race and hence is the smallest adult weasel of the species
erminea, in either the Old World or in America.

Intergradation with streatori is indicated by specimens from the
southern end of Puget Sound. These specimens are intermediate
in size between typical examples of the two races concerned.

The color of the upper parts is uniform and the color pattern
varies less than in geographically adjoining races. The white color
of the underparts is restricted to a thin line on the abdominal re-
gion, but widens out posteriorly in the inguinal region and an-
teriorly over the pectoral region, throat, chin and lower lips. The
upper Hps are brown. The brown of the upper parts extends
around in front of each foreleg, the two brown areas not quite meet-
ing on the lower throat. The above description applies to each of
the 19 specimens examined with regard to these details. Every
specimen seen in the winter coat was brown, not white.

Specimens examined. — Total number, 20, arranged by counties from north
to south. Unless otherwise indicated, specimens are in the U. S. National
Museum,

Washington. Clallam Co.: Clallam Bay, 2 ( 1\ 1'); Elwah, 2"; Johnsons
Ranch, 1*; Happy Lake, 1*; Boulder Lake, 2*; near head of Soleduc River, 4500
ft., 1; 12 mi. S Port Angeles, V. Jefferson Co.: Hayes Cr., 2000 ft., Elwah
River, 2; head N Fork Quinault River, 4000 ft., 1; Duckabush, 3; N Fork
Skokomish River, 1. Mason Co.: Lake Cushman, 2°; 4 mi. S Olympia, 1.

Mustela erminea streatori (Merriam)

Ermine

Plates 5, 6, 7, 12, 13 and 14

Putorius streatori Merriam, N. Amer. Fauna, 11:13, pi. 2, figs. 5, 5a, 6,

6a, June 30, 1896.
Putorius cicognanii, Baird, Mamm. N. Amer., p. 161, 1858 (part imless

no. 2395 was a female of M. frenata).
Putorius pusillus, Baird, Mamm. N. Amer., p. 159, 1858 (part).
Putorius (Gale) vulgaris, Coues, Fur-bearing animals, p. 102, 1877 (part).
Mustela streatori streatori. Miller, U. S. Nat. Mus. Bull., 79:96, December

31, 1912; Grinnell, Univ. CaUfomia Publ. Zool., 40:101, September 26,

1933.
Mustela cicognanii streatori. Hall, Murrelet, 12:22, January, 1931; Hall,

Univ. California Publ. Zool., 38:417, November 8, 1932.
Mustela erminea streatori. Hall, Joum. Mamm., 26:77, February 27, 1945;

Hall, Joum. Mamm., 26:181, July 19, 1945.
Mustela rixosa. Beer, Joum. Mamm., 29:296, August 31, 1948.

1. Mus. Vert. Zool., Univ. California 4. Field Museum of Natiu-al History

2. Univ. Washington Museum of Zoology 5. Museum of Zoology, Univ. Michigan

3. Charles R. Conner Museum

156 University of Kansas Publs., Mus. Nat. Hist.

Type. — Male, adult, skull and sldn; no. 76646, U. S. Nat. Mus., Biol.
Surv. Coll.; Mount Vernon, Skagit Valley, Skagit County, Washington; Feb-
ruary 29, 1896; obtained by D. R. Luckey, original no. 3.

The skull is unbroken and the teeth all are present and entire. The skin,
in brown winter pelage, is stuffed and in good condition.

Range. — Western Washington along eastern side of Puget Sound, western
Oregon from the Cascades to the coast, and northwestern California south
in the humid coastal district nearly to the Golden Gate. See figures 25,
27 on pages 95, 149.

Characters for ready recognition. — Differs from M. e. anguinae, in male,
by sagittal crest present and hind foot ordinarily less than 33.5, in female
by hind foot less than 27.5, basilar length less than 30.2; from M. e. fallenda,
in both sexes, by black tip of tail less than half of length of tail-vertebrae,
in males hind foot less than 33.7, tympanic bulla about same length as, in-
stead of longer than, upper tooth-rows; weight of skull less than 1/4 grams,
in female weight of skull less than 0.7 grams, length of lateral side of P4
less than 4 mm.; from M. e. ohjmpica, by larger size, in males hind foot
more than 33.0, basilar length ordinarily more than 32.5, in females by hind
foot ordinarily longer than 24, by breadth of rostrum more than 8.6, depth
of braincase at posterior border of upper molars more than 7.6; from M. e.
giilosa and muricus, in both sexes, by upper Ups brown (not white), light
color of underparts ex-tending down hind leg no farther than knee, depth of
skull at posterior border of upper molars more than 7.7 in females and
ordinarily more than 9.6 in males, further from muricus by tail more than
62 in males and more than 49 in females; from M. e. invicta by upper Ups
wliite (not brown), in males hind foot more than 36 and basilar length more
than 35, in females hind foot more than 29.5 and basilar length more than
30.5.

Description. — Size. — Male: Twelve adults from Blaine and Tillamook,
Oregon, yield average and exlieme measurements as follows: Total length,
255 (245-275); length of tail, 72 (64-80); length of hind foot, 31.5 (30.0-
33.5).

Female: Seven adults from Blaine and Tillamook, Oregon, yield average
and extreme measurements as follows: Total length, 214 (193-230); length
of tail, 55 (50-63); length of hind foot, 25 (24-27).

Color. — Winter and summer pelages indistinguishable; upper parts uni-
form and ranging from Raw Umber to slightly darker (16n), and about tones
1 to 3 of Dark Chocolate of Oberthiir and Dauthenay, pi. 342; underparts
white, in summer rarely with a faint buffy suffusion in pectoral region; color
of underparts extends from chin, and often lower Hps, posteriorly to inguinal
region, distally on posterior sides of forelegs onto antipalmar faces of toes
(sometimes interrupted at and above wrist) and on medial sides of hind
legs hardly to knee. Least width of color of underparts averaging, in twelve
adults from Blaine and Tillamook, 10 (0-47) per cent of greatest width of
color of upper parts. Black tip of tail, in same series, averaging 28 (24-33)
mm. which is 40 (34-47) per cent of length of tail-vertebrae.

Skull. — Male (based on 12 adults): See measurements and plates 5-7.
As described in Mustela erminea richardsonii except that: Weight, 1.1 (1.0-

I

MUSTELA ERMINEA 157

1.2) grams; basilar length, 33.2 (32.5-33.8); length of tooth-rows more or
less than (about same as) length of tympanic bulla.

Female (based on 7 adults): See measurements and plates 12-14. As
described in Mustela erminea richardsonii except that: Weight, 0.64 (0.60-
0.67) grams; basilar length, 28.5 (27.6-29.5); breadth of rostrum more than
30 per cent of basilar length.

Comparison with anguinae, fallenda, olympica, gulosa and
muricus is made in accounts of those subspecies.

Remarks. — This weasel is rare in collections and the best mate-
rial of it was obtained by Alex Walker in Tillamook County, Ore-
gon, where he resides. The almost ideal series of 30 specimens
showed the range of secondary sexual, age, and individual varia-
tion expectable in the small ermines of the Pacific Coast of the
United States and was the means of allowing satisfactory decision
on questions of classification in the related subspecies in which in-
dividuals are of comparable size.

Intergradation with each of the geographically adjoining sub-
species, olympica, fallenda, invicta, gulosa and muricus is shown
by specimens examined. With the last mentioned subspecies, in-
tergradation is shown by two specimens from as far south as Siski-
you County, California, assigned to muricus.

The application of the name streatori is difficult because it was
based on a specimen from a place where two cHnes cross. The
north-south cline is one of size which decreases to the south. The
east- west cline is one of intensity of color, the westernmost ( coastal )
population being the most intensely colored. The type locality of
streatori is at the place where two lines perpendicular to one an-
other, and representing the two clines, cross. This intersection is
near the place where the ranges of several subspecies meet. The
nomenclatural question is, to which one of 6 subspecies should the
name streatori apply. Specimens from barely within the geographic
boundaries of four of these subspecies so closely resemble topo-
types of streatori that a student with material at his disposal from
only the area about Puget Sound naturally would apply the name
streatori to all of his specimens, and knowing even of the arrange-
ment adopted in the present account the student will have difficulty
in identifying his specimens according to it. Not only will the
student find the arrangement difficult, but probably unsatisfactory
if he thinks of streatori as being the kind of animal represented by
topotypes. I conceive of topotypes of streatori as being nontypical
of the subspecies; they are intergrades with fallenda. My aim was
initially to work out the geographic ranges of subspecies and only

158 University of Kansas Publs., Mus. Nat. Hist.

subsequently to apply names, according to which type localities
fell within the previously determined geographic ranges. By this
procedure no greater weight was given to a holotype and to topo-
types than to specimens from any other locahty.

Of the 40 specimens seen in winter pelage, only one is white. It
is from Darrington in the Cascade Mountains of Washington. The
39 others are brown and I doubt that the white pelage ever occurs
in the low coastal territory included within the geographic range
of streatori. This subspecies resembles anguinae and olympica in
the great extension of area of the dark-colored upper parts at the
expense of the area of the light-colored underparts. The usual ar-
rangement is one where the brown of the two sides nearly meets
on the midventral line leaving a sizable, inguinal area of light color
connected by a thin line to the sizable area of hght color on the
pectoral region. The light color of the pectoral area ordinarily is
continuous with the light-colored area of the throat and chin but
the dark color of the upper parts extends around in front of each
foreleg. These extensions of dark color meet on the chest in only
2 of the 56 specimens examined in this regard. Across the abdo-
men the dark color is continuous in 4 of the 56 specimens. The
lower lips are brown instead of white in only 3 individuals and in
2 of these the lip of one side is brown and its opposite is white.
The variation in color-pattern is less than in anguinae or than in
fallenda.

Specimens examined. — Total number, 63, arranged alphabetically by states,
then by counties from north to south in each state. Unless otherwise indicated,
specimens are in the U. S. National Museum.

California. Humboldt County: 10 mi. NE Carlotta, 1\ Mendocino County:
Russian Gulch Slate Park, 1\ Sonoma County: Mouth of Gualala River, V.

Oregon. Clatsop Co.: Astoria, 1. Tillamook County: Tillamook, 16 (14^
1"); Blaine, 12 {1\ 2', 1*, 2"). Washington Co.: Beaverton, 1°; Forest Grove,
1'. Clackamas Co.: Oregon City, 1*. Lincoln Co.: Newport, 1. Linn County:
Sico, 1*. Lane Co.: Vida Fish Hatchery, 2"; McKenzie Bridge, 1°; Mercer, 1".
Klamath County: Deschutes River, 6 mi. E Crescent Lake, 1*. Douglas Co.:
Gardiner, 1'. Curry Co.: Port Orford, 1; Gold Beach, 2'.

Washington. Skagit Co.: N end Whidby Island opposite Deception Pass, 1;
Hamilton, 4; Mt. Vernon, 3. Snohomish County: Oso, 550 ft., 1; Darrington,
600 ft., 1. Pacijic County: Wallicut River, 2 mi. E llwaco, 1'. Wahkiakum
Co.: 4 mi. E. Skamokawa, 3\ Coivlitz County: 4 mi. E mouth Kalama River,
2'; 6 mi. E mouth Kalama River, 1\ Skamania Co.: 15 mi. N Govt. Springs,
1300 ft., 1.

1. Mus. Vert. ZooL, Univ. California 6. Field Museum of Natural History

2. Collection of Alex Walker 7. Collection of O. J. Murie

3. Donald R. Dickey Collection 8. Collection of Stanley G. Jewett

4. Univ. Kansas Mus. Nat. History 9. University of Oregon

5. Museum of Zoology, Univ. Michigan 10. Museum of Comparative Zoology

MUSTELA ERMINEA 159

Mustela erminea gulosa Hall

Ermine

Plates 5, 6, 7, 12, 13 and 14

Mustela erminea gulosa Hall, Joum. Mamm., 26:84, February 27, 1945; Hall,

Joum. Mamm., 26:181, July 19, 1945.
Putorius streatori Merriam, N. Amer. Fauna, 11:14, June 30, 1896.

Type. — Male, subadult, skull and skin; no. 81998, U. S. Nat. Mus., Biol. Surv.
Coll.; Trout Lake, Klickitat County, Washington; February 3, 1897; obtained
by P. Schmid, original no. 147.

The skin is in brown winter pelage, and appears to have been made up
from a skin split along the mid-ventral line from the anus to the forelegs. It
probably was dried by a trapper, is well made, and lacks a patch of hair on
the left flank but otherwise is in good condition. The skull lacks the central
part of the left zygomatic arch and the posterior two-tliirds of the right one.
The right m2 is represented only by an abortive stump or the broken root,
and il and i2 on each side are absent; otherwise, the teeth all are present
and entire.

Range. — Cascades of Washington from northeastern King County south to
Mount Adams. See figures 25, 27 on pages 95, 149.

Characters for ready recognition. — Differs from M. e. invicta and fallenda,
in both sexes, by anterior margin of tympanic bulla flush with squamosal rather
than projecting below floor of braincase (difference shght in females), in males
hind foot less than 33.5, weight of skull less than Di grams, basilar length less
than 33.9, in females by total length less than 222, hind foot shorter than 26,
weight of skull less than 0.7 grams, basilar length less than 29; from M. e.
muricus, in both sexes, by upper parts darker, tone 4 of Chocolate or darker
(see description of color) least width of hght-colored underparts averaging
one-third instead of approximately two-thirds of greatest width of dark-colored
upper parts, in males, on the average, tail more than 65, weight of skull more
tlian 0.90 grams, basilar length more than 30.8 mm.; from M. e. streatori, in
both sexes, by upper hps white (not brown), hght color of underparts extend-
ing down hind legs below knee, depth of skull at posterior border of upper
molars less than 7.7 in females and ordinarily less than 9.6 in males.

Description. — Size. — Male: One adult and four subadults from Mount
Rainier yield average and extreme measurements as follows: Total length, 253
(238-266); length of tail, 75 (70-83); length of hind foot, 31.5 (30-33).
Corresponding measurements of 9 subadults from Trout Lake are: 257 (233-
282); length of tail, 76 (56-83); length of hind foot, 30.2 (26-33).

Female: Of adults, 2 from Mount Rainier and 2 from Trout Lake measure
as follows: Total length, 202, 203, 216, 210; length of tail, 54, 52, 57, 51;
length of hind foot, 24, 24, 25, 24. The averages for these females are 208,
54, 24.3.

Color. — As described in Mustela erminea richardsonii except that color
sometimes brown in winter (with more smoky tinge than summer coat); upper
parts ranging from tone 2 through tones 3 and 4 of Dark Chocolate (pi. 342)
into tone 4 of Chocolate (pi. 343) of Oberthiir and Dauthenay; underparts
(always white in winter) in summer Sulphur Yellow or more whitish; least

160 University of Kansas Publs., Mus. Nat. Hist.

width of color of underparts averaging, in 5 males from Mount Rainier, 31
(18-45) per cent of greatest width of color of upper parts. Black tip of tail,
in same series, averaging 34 (29-40) mm., wliich is 45 (41-50) per cent of
length of tail-vertebrae.

Skull. — Male (based on 2 ad. and 13 sad.): See measurements and plates
5-7. As described in Mustela erminea richardsonii except that: Weight, 1.0
(0.95-1.16) grams; basilar length, 32.3 (30.9-33.4); length of tooth-rows more
or less than (about equal to) length of tympanic bulla.

Female (illustrated by 5 adults): See measurements and plates 12-14. As
described in Mustela erminea richardsonii except that: Weight, 0.59 (0.53-
0.65) grams; basilar length, 28.1 (27.8-28.4); breadth of rostrinn ordinarily
more than 30 per cent of basilar length.

In comparison with streatori, skulls of males and females aver-
age smaller in every cranial measurement taken. Teeth of about
same size and males 9 per cent, and females 8 per cent, hghter. In
relation to basilar length, skull of female shallov^er, tympanic bul-
lae slightly shorter and, on the average, zygomata less expanded.

In comparison with muricus, males average larger in every meas-
urement taken; 23 per cent heavier; in relation to other dimensions,
braincase shallower at anterior end of basioccipital. Females are
of about equal size; in relation to other dimensions, braincase shal-
lower and mastoid and zygomatic breadths less.

Comparisons with invicta and fallenda have been made in the
accounts of those subspecies.

Remarks. — This is not a strongly marked race and in most of the
characters used for differentiating it from other races it resembles
either streatori to the west or muricus to the southeast. Neverthe-
less, there is a geographic area, the southern Cascades of Washing-
ton, tliroughout which individual characters are combined in es-
sentially the same way and there are a few features, for instance,
smaller skull of the female, in which gulosa differs from either of
its close relatives. In view of these circumstances and because the
animals can not well be included in the subspecies streatori or
muricus, gulosa is recognized as distinct. The races gulosa and
olympica are what might be termed weakly differentiated sub-
species in contrast to the stiongly differentiated subspecies streatori
and muricus.

Of the 21 specimens in winter pelage, 17 are white and four
are brown. The brown winter coat is distinctly paler, with more
of a smoky tinge, than the brown summer pelage. The light-
colored underparts are narrower than in the subspecies immediately
to the east but are wider than in the coastal forms to the west.
The dark color of the upper parts extends onto the chest in front

MUSTELA ERMINEA 161

of the forelegs, as in the coastal forms, in only one of the 13 speci-
mens in summer pelage and in it on one side only. The black tip
of the tail is short as in the coastal fonns. One specimen is in
transitional pelage. It has acquired approximately half of the
white winter pelage and was taken on October 12, 1897, at Kee-
chelus Lake.

Specimens examined. — Total number, 38, arranged by counties from north
to south. Unless otherwise indicated, specimens are in the U. S. National
Museum.

Washington. King County. 2 mi. E Skykomish, 2\ Kittitas Co.: Keechelus
Lake, 3 (1'); Martin, 1'; Easton, 3. Fierce Co.: James Lake, 4370 ft., Mt.
Rainier, 1; Glacier Basin, 5935 ft., Mt. Rainier, 1; Meslers Ranch, 2000 ft., 1 mi.
W Rainier Park, 1. Lewis Co.: Mt. Rainier Nat'l Park, 5 (1 each from:
Paradise Park, 5400 ft.; Reflection Lakes, 4900 ft.; Ohanapecosh [Hot] Springs,
2000 ft.; Tahoma Creek, '; Bear Prairie); also in Mt. Rainier Nat'l Park, Long-
mire, 3 (!', 1*). Skamania Co.: Mt. St. Helens, 6000 ft., 1. Klickitat Co.:
Trout Lake, 18.

Mustela enninea muricus (Bangs)

Ermine

Plates 7, 8, 12, 13, 14 and 41

Putorius (Arctogale) muricus Bangs, Proc. New England Zool. Club, 1:71,

July 31, 1899.
Putorius streatori leptus Merriam, Proc. Biol. Soc. Washington, 16:76,

May 29, 1903. Type from Silverton, San Juan County, Colorado.
Putorius muricus, Stephens, Cahfomia Mammals, p. 248, 1906.
Putorius cicognani, Taylor, Univ. CaUfomia Publ. Zool., 7:298, June 24,

1911.
Mustela streatori leptus, Miller, U. S. Nat. Mus. Bull., 79:96, December

31, 1912; Bailey, N. Amer. Fauna, 35:48, September 5, 1913; Dixon,

Joum. Mamm., 12:72, February 12, 1931; Whitlow and Hall, Univ.

California Publ. Zool., 40:246, September 30, 1933.
Mustela muricus. Miller, U. S. Nat. Mus. Bull., 79:96, December 31, 1912;

Kellogg, Univ. California Publ. Zool., 12:358, January 27, 1916.
Mustela cicognanii lepta. Dice, Joum. Mamm., 1:12, November 28, 1919;

Hall, Mamm. Nevada, p. 184, July 1, 1946.
Mustela rixosa, Seton, Joum. Mamm., 14:70, February 14, 1933.
Mustela cicognanii leptus, Miller, Joum. Mamm., 14:368, November 13,

1933; Bailey, N. Amer. Fauna, 55:293, August 29, 1936.
Mustela erminea murica. Hall, Joum. Mamm., 26:84, February 27, 1945;

Hall, Joum. Mamm., 26:181, July 19, 1945.

Type. — Male, young, skull and skin; no. 9146, collection of E. A. and
O. Bangs in Mus. Comp. Zool.; Echo, 7500 ft.. El Dorado County, Cahfomia;
July 15, 1897; obtained by W. W. Price and E. M. Nutting.

The skull has a fracture along the sagittal suture and fractures on the
left side of the braincase but these have been glued, and no part of the skull
is missing except in the region of the right P4 which part has been shot away.
On the left side m2 never developed. Excepting this tooth and the right P4,

1. Collection of Walter W. Dalquest 3. Mt. Rainier Nat'l Park Collection

2. Acad. Nat. Sciences of Philadelphia 4. Univ. Washuigton Museum of Zoology

6—3758

162 University of Kansas Publs., Mus. Nat. Hist.

all the teeth are present and entire. The skin is well made but has the
soles of the hind feet turned up.

Range. — Near 5300 feet (Denver) to 11000 feet (Santa Fe Baldy); typi-
cally boreal but taken in Upper Sonoran Life-zone in winter at Denver; from
central and southwestern Montana, southern Idaho, and Blue Mountains of
southeastern Washington southward east of the Cascade Divide through the
Salmon River Mountains and Sierra Nevada at least into Fresno Coimty
of California, in the Great Basin to central Nevada, in the Rocky Mountains
into northern New Mexico; eastward to the Black Hills. See figure 25 on
page 95.

Characters for ready recognition. — Differs from M. e. invicta by hind
foot less than 36 and basilar length less than 35 in males and by hind foot
less than 29.5 and basilar length less than 30.5 in females; from M. e. gulosa,
in both sexes, by upper parts lighter, tone 2 of Chocolate or lighter (see de-
scription of color), least wddth of hght-colored underparts averaging about
two-thirds instead of one-third of greatest width of dark-colored upper parts,
in males, on the average, tail less than 65, weight of skull less than 0.90
grams, basilar length less than 30.8 grams; from M. e. streatori, in both sexes,
by upper lips white (not brown), hght color of underparts extending down
hind leg below knee, depth of skull at posterior border of upper molars less
than 7.7 in females and ordinarily less than 9.6 in males, tail less than 62
in males and less than 49 in females.

Description. — Size. — Male: An adult from Black Butte, Cahfomia, meas-
ures: Total length, 227; length of tail, 55; length of hind foot, 27. Cor-
responding measurements of another from Wheeler Peak, Nevada, are: 220,
56, 26. Two subadults from Colorado, one from Crested Butte and another
from Coventry, measure, respectively, as follows: 238, 227; 66, 60; 30, 30.
An adult from Wheeler Peak, Nevada, weighs 57.7 grams and another from
2 mi. W Black Butte, Cahf., 54.5 grams.

Female: Two adults from Teton County, Wyoming, measure: Total
length, 205, 200; length of tail 52, — ; length of hind foot, 23, 23.7. A
subadult from 9/2 mi. E Pocatello, Idaho, measures: 197, 50, 25. An adult
from Wheeler Peak, Nevada, has corresponding measurements of 190, 42,
23, and weighs 33.8 grams.

Color. — As described in Mustela erminea richardsonii except that upper
parts tone 2 or lighter of Chocolate of plate 343 of Oberthiir and Dauthenay;
underparts white. Pale Buff or with faint wash of Sulphur Yellow; least
width of color of underparts in male from Black Butte and one from Wheeler
Peak, amounting to 65 and 59 per cent of greatest width of color of upper
parts. Black tip of tail, respectively, 28 and 33 mm., which amounts to 51
and 59 per cent of length of tail-vertebrae. In two adult females, one from
Teton County, Wyoming, and one from Wheeler Peak, Nevada, the least
width of the underparts amounts to 55 and 60 per cent of the greatest width
of color of upper parts. Black tip of tail, respectively, 23 and 19 mm., which
amounts to 44 and 45 per cent of length of tail-vertebrae.

From the other subspecies of small-sized weasels of more northwestern
occurrence, namely anguinae, fallenda, olympica, streatori and gulosa, muricus
differs in lighter color of upper parts, wider light-colored underparts and rel-
atively longer black tip of tail.

MUSTELA ERMINEA 163

Skull. — Male (illustrated by 5 adults in table of measurements, which
see): See plate 7. As described in Mustela erminea richardsonii except that:
Weight, 0.78 (Wheeler Peak) and 0.85 (Black Butte) grams; basilar length,
30.6 (29.8-31.2); length of tooth-rows more or less than (approximately equal
to) length of tympanic bulla.

Female ( illustrated by 6 adults in table of measurements, which see ) :
See plates 12-14. As described in Mustela erminea richardsonii except that:
Weight, 0.60 (0.575-0.645); basilar length, 28.0 (27.3-29.4); breadth of
rostrum approximately 30 per cent of basilar length.

In comparison with streatori, males average smaller in every meas-
urement taken with no overlap in most dimensions; 25 per cent
lighter; anterior margin of tympanic bulla more nearly flush with
squamosal, that is to say less protruded from braincase; in re-
lation to other dimensions of skull, braincase shallower anteriorly
(at plane of last molars) and deeper posteriorly (at anterior end
of basioccipital ) . Females average smaller in every measurement
taken except mastoid and zygomatic breadths which are actually
more; 6 per cent lighter; in relation to other parts of skull, pre-
orbital and interorbital parts slightly smaller; in relation to length
of skull, braincase shallower. Comparison with invicta and gulosa
is made in the accounts of those subspecies.

Remarks. — The smallest males of the entire species are of this
subspecies and the females of it are barely larger than those of
olympica and gulosa and hence are among the three smallest.
The material now available consists only of one or a few specimens
from each of several widely separated localities. If as many speci-
mens per unit area were available as there are of the species M.
erminea from southern British Columbia, geographic variation
warranting the division of muricus into more than one subspecies
might be revealed. Evidence pointing in this direction is com-
prised in the pale color and small size of the pair of adults from
Wheeler Peak on the eastern border of Nevada; the suggestion is
that there is a distinct pale race of small individuals in the isolated
spots of boreal life-zone in the mountains of the desert. The
color and size of the specimens from the Toyabe Mountains, and
that from the Pine Forest Mountains, both places also in Nevada,
nevertheless, lend no support to this suggestion. Comparison of
specimens from the Rocky Mountains of Colorado with those from
the Sierra Nevada of California gives no basis for recognizing more
than one subspecies. Therefore, Putorius streatori leptus Merriam
with type locality at Silverton, San Juan County, Colorado, falls as
a synonym of the earlier named Tutorius ( Arctogale ) muricus Bangs
with type locality at Echo, El Dorado County, California. Further-

164 University of Kansas Publs., Mus. Nat. Hist.

more, specimens from northern New Mexico, the southernmost
known area of occurrence for the subspecies (and for the species),
are as large as specimens from far north in the range of the sub-
species, say, in northwestern Wyoming; there is therefore no evi-
dence of progressive decrease in size to the southward as in advance
of study I supposed existed in muricus. This erroneous supposi-
tion was held because I knew that there was a decrease in size to
the southward in the species as a whole and also in each of the
subspecies richardsonii and invicta directly to the north of muricus.
Intergradation with invicta is shown by specimens from south-
western Montana. Where the margins of the geographic ranges of
invicta and muricus approach one another elsewhere, low-lying
territory, zonally unsuited to the existence of the species, occurs
along the Snake and Columbia rivers, and precludes any chance of
intergradation except around the head of the Snake River Plains.
Two specimens, here referred to muricus, from Siskiyou County,
California, in both color and cranial characters, are intergrades
with streatori and might be referred with almost equal propriety
to streatori.

Specimens examined. — Total number, 52, arranged alphabetically by states,
then by counties from north to south within each state. Unless otherwise in-
dicated, specimens are in the Museum of Vertebrate Zoology, University of
California at Berkeley.

California. Siskiijou County: head of Rush Creek, 6400 ft., 1; Castle Lake,
5434 ft., 1. Teha7na County: 2 mi. W Black Butte, 6800 ft., 1. Placer County:
ridge W of Tahoe Pines, Lake Tahoe, 1; Blackwood Creek, 6250 ft., near Tahoe
Pines, 1. El Dorado Co.: Fallen Leaf Lake, 6500 ft, 1'; Echo, F. Tuolumne
Co.: Ten Lakes, 9200 ft., Yosemite Park, 1. Mariposa Co.: Vogelsang Lake,
10350 ft., Yosemite Park, 1. Mono County: Mammoth, 1'.

Colorado. Rio Blanco Co.: Marvine, L Boulder Co.: Camp Albion, 10600
ft., 1'; Boulder, V. Denver Co.: Denver, 1\ Park County: Jefferson, 1'.
Gunnison Co.: near Placita in Gunnison County, 1'; Crested Butte, 9000 ft.,
3 ( r, 2'). El Paso County: Turkey Creek, SW Colorado Springs, 6000 ft., 1'.
Chaffee Co.: Arp[b]ourville, 1"; Plancock, 1. Montrose County: Coventry,
6800 ft., 1". San Juan Co.: Silverton, 1°; in San Juan County above timber-
hne, r.

Idaho. Bannock County: West Fork of Rapid Creek, 9)2 mi. E Pocatello, 1.

Montana. Meagher Co.: Camas Creek, Big Belt Mts., 4 mi. S Ft. Logan, 1'.
Beaverhead Co.: Donovan, 1°. County in question: Yellowstone Park, l^

Nevada. Humboldt Co.: Alder Creek, 6000 ft., Pine Forest Mts., 1. Ormsby
County: 'A mi S Marietta Lake, 8150 ft., 1. Nye Co.: South Twin River, Toy-
abe Mts., l^ White Pine County: Baker Creek (8500 ft., 8675 ft., 11100
ft.), 3.

New Mexico. Taos Co.: Twining, 10700 ft., 1°. Sandoval County: 9 mi. E
Cuba, 9000 ft., 1. Santa Fe Co.: Saddle S of Santa Fe Baldy, 11000 ft., Santa
Fe Range, 1".

Oregon. Wasco Co.: Mill Creek, 20 mi. W Warmsprings, T. Klamath Co.:
Fort Klamath, 1".

MUSTELA ERMINEA 165

South Dakota. Peiminsfon County. 4 mi. SE Hill City, 5300 ft., 2"; Pfan-
der's Ranch, 3 mi. SSE Hill City, 5300 ft., 1"; Palmer Gulch, 3 mi. SE Hill
City, 5300 ft., 1"; Spring Creek, 2 mi. W Oreville, 5500 ft., 1". Custer County:
a mi. E Sylvan Lake, 6250 ft., 1".

Washington, Columbia County: Butte Creek, 1; Stayawhile Spring, 5150
ft., 1.

Wyoming. Crook County: 5 mi. NW Sundance, 5900 ft., 1". Teton
County: Whetstone Creek, 2"; M mi. E Moran, 6700 ft., 1". Sublette County:
Ji mi. NE Pinedale, 7500 ft., 1". Albany County: 30 mi. N and 10 mi. E
Laramie, 6560 ft., 1"; 26 mi. N and 4Ji mi. E Laramie, 6960 ft., 1". Carbon
County: 8 mi. N and 19M mi. E Savery, 8800 ft., 2".

Mustela erminea? angustidens (Brown)
Plates 7, 12, 13 and 14

Putorius cicognanii angustidens Brown, Mem. Amer. Mus. Nat. Hist.,

9 (pt. 4):181, pi. 17, 1908.
Mustela cicognanii angustidens. Hay, Iowa Geol. Surv. Bull., 23:32, 1914;

Hay, Carnegie Inst. Washington, Pub. no. 322A:252, October 15, 1924;

Hay, ibid.. Pub. no. 390 (vol. 2): 528, 1930; Hall, ibid.. Pub. no.

473:111, 112, November 20, 1936.

Type. — Female, adult, skull and lower jaws lacking zygomata, right P2
and incisors, no. 12432, Amer. Mus. Nat. Hist.; from Conard Fissure, four
miles west of Willcockson, Newton County, Arkansas; obtained sometime in
the period 1903 to 1905 inclusive (see plates 8, 14).

Range. — Known only from the Pleistocene deposit in Conard Fissure, at
the type locality in northern Arkansas.

Description. — Skull. — Male (based on nos. 12437, 12441 and 12444): See
measurements and plates 7 and 8; weight, unknown; basilar length, 38.1
(36.6-39.2); length of tooth-rows more tlian length of tyinpanlc bulla; breadth
of rostrum measured across lacrimal processes less than a third of basilar
length; interorbital breadth ordinarily equal to distance between glenoid
fossa and posterior border of external auditory meatus; zygomatic breadth
probably averaging approximately the same as distance between last upper
molar and jugular foramen.

Female (based on nos. 11766 and 12435): See measurements and plates
8, 12-14; weight, unknown; basilar length, 34.0 (32.5-35.1); length of tooth-
rows more than length of t>'mpanic bulla; breadth of rostrum about equal
to (more or less than) 30 per cent of basilar length; interorbital breadth less
than distance between glenoid fossa and posterior border of external auditory
meatus; zygomatic breadth probably less than distance between last upper
molar and jugular foramen.

Comparison of the cranial description given above with those of the Ameri-
can races of erminea from the far north vdll show that many characters are held
in common — more than vvdth more southern subspecies of erminea.

1. Collection of Lloye H. Miller 7. Collection of Jack C. vonBloeker

2. Museum of Comparative Zoology 8. Collection of Edward R. Warren

3. Donald R. Dickey Collection 9. San Diego Society of Natural History

4. Field Museum of Natural History 10. Acad. Nat. Sciences of Philadelphia

5. United States National Museuin 11. Museum of Zoology, Univ. Michigan

6. Colorado Museum of Natural History 12. Univ. Kansas Mus. Nat. History

166 University of Kansas Publs., Mus. Nat, Hist.

Remarks. — The ten specimens studied by the writer fall into two
groups of six larger individuals and four smaller. Upon comparing
these with each sex of the three species of American Recent weasels,
frenata, erminea and rixosa, it is seen that size, and to some degree
shape, rule out of consideration both sexes of rixosa and also males
of frenata. Thus we are left with females of frenata and males and
females of erminea. So far as size is concerned, it can be assumed
that the larger specimens are females of frenata and that the smaller
are males of erminea. This assumption has in its favor also, the
fact that the postglenoidal length of the skull accords with that in
Recent specimens. The difference in this regard in Recent animals
is that the postglenoidal length of the skull, expressed as a per-
centage of the total ( condylobasal ) length of the skull, amounts to:
in frenata in erminea

(J ordinarily less than 46 $ ordinarily more than 46

5 less than 47 5 more than 48

In the fossils the percentage for the larger skulls is 46; for the
smaller skulls it is 48.

It may be that the ten fossil skulls are six female frenata and four
male erminea but I think not. In the first place a skull of different
shape, seemingly of the frenata stock, is known from the deposit
and it is almost certain that two subspecies of the same species
would not occur at the same place at the same time. It is possible,
of course, that parts of the deposits were laid down at times so far
apart that a shift in geographic range of two subspecies had oc-
curred. This one skull, seemingly of the frenata stock, is the type
of Piitoritis gracilis Brown (see p. 404) and was regarded as the
only known specimen of gracilis. Regardless of the specific identity
of this one specimen named gracilis, the chances of obtaining other-
wise from a deposit, like that in Conard Fissure, six females of
frenata and four males of erminea without a male frenata or a fe-
male of erminea coming to light are so slight as strongly to incline
me to the view that the six larger specimens are males of the same
species to which the 4 smaller specimens belong. By either this
interpretation, or the one initially considered (of female frenata
and male erminea), the animals from the fissure are at least sub-
specifically distinct from any American Recent weasel. Further-
more, by this latter interpretation each sex of this weasel, angiis-
tidens, is intermediate between the frenata and erminea stocks in
the feature of postglenoidal length which feature, at any place

MUSTELA ERMINEA 167

where the two Recent species occur together, serves to distinguish
one from the other. In the northernmost subspecies of erminea
(arctica for example) the postglenoidal length in some males is
no longer than in males of frenata. Considering general size, an-
gustidens agrees better with erminea than with frenata and this
circumstance has influenced me to place angtistidens as a sub-
species of erminea.

Today, erminea is not known to occur nearer Conard Fissure
than northern Iowa, more than 400 miles to the northward. In
comparison with the race there, bangsi, males of angustidens are of
approximately the same size but in the shorter distance between
the glenoid fossa and anterior margin of the tympanic bulla, and
also in the lesser postglenoidal length of the skull, angustidens re-
sembles the northernmost American subspecies of erminea. Fe-
males of angustidens differ more from any living weasel than the
males do. The females are much larger than those of bangsi, and
among living American races of erminea most closely resemble
intergrades between arctica and richardsonii which intergrades are
found approximately 1700 miles to the north of Conard Fissure.
In females, the preorbital part of the skull in M. e. arctica is
broader and in M. e. richardsonii narrower than in angustidens.
If it seems strange that females of angustidens resemble one sub-
species whereas males, in size, resemble another subspecies almost
a thousand miles distant, it should be remembered that the degree
of sexual dimorphism varies much from one subspecies to another
in the Recent animals. An example is furnished by Mustela er-
minea fallenda and Mustela erminea invicta.

The assemblage of mammals from Conard Fissure includes sev-
eral species of boreal predilections which, like Mustela erminea,
now occur only much farther north than Arkansas. At one time
the edge of the sheet of ice was only about 200 miles north of
Arkansas. It may be significant that the cranial characters of the
female ermine from the Fissure, and qualitative cranial characters
of males from there, are most nearly approximated among Recent
weasels by those which live along the southern edge of the frozen
tundra.

In view of what has been said, the possibility should be consid-
ered that the distinctive cranial features of angustidens may be the
result of evolutionary change in time as well as of geographic varia-
tion resulting from horizontal placement.

168 University of Kansas Publs., Mus. Nat, Hist.

MUSTELA RIXOSA Bangs

Least Weasel

(Synonymy under subspecies)

Type. — Putorius rixosus Bangs, Proc. Biol. Soc. VVasliington, 10:21, Feb-
ruary 25, 1896.

Range. — From Norway and Switzerland eastward through Sibera and all
the way across North America, but unknown from Iceland, Greenland and
the Arctic islands west of Greenland; in North America, from the Arctic Life-
zone south to Central British Columbia, Montana and into parts of the Upper
Austral Life-zone as in the eastern half of the continent.

The southern extension of range in the Appalachians (to North Carolina)
is not duplicated in the Rocky Mountains of western North America probably
because the region there suitable for rixosa south of Central British Colunlbia
and Montana is occupied by the almost equally small Mustela erminea muricus
and related subspecies which seem to fill the ecological role that rixosa plays
where it occurs. The small size of females of M. erminea cicognanii in New
England may similarly account for the absence of rixosa there.

Characters for ready recognition. — Differs from both Mustela er-
minea and Mustela frenata by tail a fourth or less of length of head
and body and without a black tip ( at most a few black hairs at ex-
treme tip in rixosa), and from M. frenata and from M. erminea in
regions where it and rixosa occur together, by basilar length of skull
less than 32.5 in males and less than 31.0 in females.

Characters of the species. — Size small: Total length less than
250 in males and 225 in females; tail a fourth or less of length of
head and body, and without a black pencil and at most with a
few black hairs at extreme tip; caudal vertebrae 11 to 16, normally
15 in M. r. rixosa, and 11 in one M. r. eskimo examined; skull
with long braincase and short precranial portion, thus essentially
same shape as in M. erminea but the largest males of M. rixosa
always with a lesser basilar length that even the smallest females
of M. erminea or M. frenata of the same geographic area. In fact
no specimens of M. frenata have skulls so small as the largest M.
rixosa, and skulls of equal size of M. erminea and M. rixosa, for
example, M. erminea muricus of Colorado and M. rixosa eskimo of
Alaska, differ in that when the skulls are viewed from directly
above those of rixosa have the mastoid processes more prominent,
or the braincase is higher in relation to its width or both differences
together prevail. Stated in another way, comparison of skulls of
equal size of rixosa and erminea shows that in the latter the brain-
case is more nearlv flat and is wider above and in front of the

MUSTELA RIXOSA 169

mastoid processes; therefore, the greatest breadth of the braincase
equals or exceeds the mastoid breadth, whereas the reverse is
ordinarily true of rixosa.

Geographic variation. — In the Old World four subspecies are
currently recognized (see Allen, 1933:316) and the same number
is here recognized in North America. Length of the tail, length
of head and body and hind foot, breadth of the rostral part of the
skull in relation to its length, and position on the side of the head
of the line of demarcation between the dark color of the upper
parts and the white underparts, are the features in which geographic
variation has been detected. The general impression is that the
amount of geographic variation is much less than in Mustela frenata
and only slightly less than in Mustela erminea of the same geo-
graphic area.

Nomenclature. — It is exceptional for a species which occurs in
both the Old- and New-World to take its specific name from New
World material, especially if the name was proposed as recently as
1896; most circumboreal species take their names from descriptions
of European specimens. Although the least weasel, Mustela rixosa
(Bangs) 1896, seems now to be an exception, it may yet turn out
that the first available name was based on European material. Zim-
mermann (1943) shows that the least weasel actually was named
on the basis of European material long before 1896 and concludes
that the name Putorius minutus Pomel, 1853, based on a specimen
from France, is the first available name.

Because Putorius nowdays is relegated to subgeneric rank under
the generic name Mustela, we have for consideration the name-
combination Mustela minuta (Pomel). Unfortunately for Zimmer-
mann's conclusion, Mustela minuta Pomel is not available because
it is preoccupied by Mustela minuta Gervais [=z Palaeogale minuta
(Gervais), 1848-1852 — see Simpson, 1946: 2, 12], a name applied
to another species of small mustelid from the Oligocene or lower
Miocene deposits of Europe.

Some other early names thought by Zimmermann (1943:290) to
have been based on the dwarf weasel of Europe are judged to be
nomina nuda and therefore are to be ignored.

The name Mustela minor Nilsson 1820 was thought by Miller
(1912:402) to be a renaming, and hence a synonym, of Mustela
nivalis Linnaeus. If that is the case the name does not apply to
the dwarf weasel. If the name Mustela minor Nilsson was instead
based on the dwarf weasel, the name might still be unavailable, de-

170 University of Kansas Publs., Mus. Nat. Hist.

pending on rulings on secondary homonyms, because the name
might be preoccupied by [Lutra] minor Erxleben 1777 which is a
synonym of [Mustela] lutreola Linnaeus 1766. Two names seem-
ingly available for weasels, and in use for them today, which might
replace rixosa as the name of the species, are, first, Mustela boc-
camela Bechstein, 1801, of Sardinia [= Mustela nivalis hoccamela
of Miller, 1912, 405] and second, Putorius numidicus Pucheran,
1855, of Morocco and Algeria [= Mustela numidica of Allen, G.
M., 1939, 183]. As they stand in the current literature, Mustela
numidica is a species distinct from the dwarf weasel and the other
name, Mustela nivalis hoccamela, is an insular subspecies of the
mouse weasel. Zimmermann (1943:292), however, implies that
M. numidica may belong to the dwarf weasel group when he says
"Ob auch iberica Barr.-Ham. als Unterart zu 7ninuta Pom. zu stellen
ist, soil hier nicht untersucht werden, ebensowenig die von Ca-
brera vermutete Zugehorigkeit der grossen nordafrikanischen M.
numidica Puch. zur Hberica-Gruppe ". The answer to this prob-
lem requires a taxonomic, rather than a nomenclatural, decision.
Whether either M. numidica or M. hoccamela are conspecific with
the dwarf weasel I cannot at this time ascertain for want of ade-
quate specimens. Because these two names, M. hoccamela, and
M. numidica, are assigned to kinds of weasels which are currently
regarded as specifically distinct from the dwarf weasel, and because
all the other names which certainly have been assigned to Old
World populations of the dwarf weasel before 1896, so far as I
know, are nomina nuda or are preoccupied, the next available
name, Mustela rixosa (Bangs, 1896), is here employed.

Remarks. — This species may have a wider geographic range in
northeastern North America than is now known. Strong (1930:7)
writes that the Naskapi Indians of the interior country of Labrador
between Hamilton Inlet and Ungava Bay "have only one name
for weasel, me-tah-kwut, but they say there are three kinds in their
territory, a large, an intermediate, and a very small weasel. The
latter suggests the least weasel . . . which has not been re-
corded from northern Labrador."

In the northern part of the range of the species, the winter
pelage is white and the summer pelage is brown. In the southern
part of the range, that is in the range of the subspecies allegheni-
ensis, the winter pelage is either brown or white and the time of
the molt into winer pelage is irregular; each of eleven individuals
from Pennsylvania, Michigan and Ohio, taken in December, Jan-

MUSTELA RIXOSA 171

uary, February and March is mostly white but retains some con-
siderable part of the brown pelage of the previous coat on top of
the head and usually also along the midline of the entire dorsum.
These eleven animals include individuals of each sex. Of each sex,
some are adults and some are subadults. Therefore, the delayed
or incomplete fall molt, at present, cannot be correlated with
either sex or with any particular age. No wild-taken specimens of
M . erminea or of M. frenata of the same region show this delayed
or incomplete molt.

Possibly this delay or incompleteness of molt is the result of
the same cause that lies behind the birth of some M. rixosa in
midwinter. As listed below, several litters of young have been
found in midwinter. In fact it appears that in the United States,
young may be born in every month of the year although, accord-
ing to existing information, more litters are produced in spring
and in winter than in summer and autumn. Many juveniles and
young of aUegheniensis examined in study collections clearly were
born in spring but about as many seem to have been born in mid-
winter as at any other time (in the light of present knowledge)
and this is in contrast to what we know of the two other species
of American weasels since their young, so far as known, are born
in spring.

One instance is worthy of detailed comment. An adult female,
no. 783 Ohio State Museum, taken on January 31, 1931, at Vinton,
Meigs County, Ohio, bears the following notation on the attached
label "nest plowed out of ground. Very small yng escaped —
marked like parent. 5 was nursing." The enlarged mammae
on the dried skin substantiate the statement that the female was
nursing young. She has a brown mask continuous from one ear
through the eye, across the forehead and through the other eye
to the opposite ear. On each side of the body a stripe of brown
5 to 10 mm. wide extends from the upper part of the foreleg back
to the thigh and base of the tail, uniting there with its opposite
and covering the tail. There are a few spots of brown on the
shoulders, and nmip and one on the middle of the back. Other-
wise the specimen is white. One implication of the statement
on the label that the young which escaped were marked like
the parent (presumably this female parent) is that this female is
a partial albino. I am more inclined, however, to the view that
there was an unseasonable activity of the particular glands of in-
ternal secretion the hormones of which promote embryonic growth

172 University of Kansas Publs., Mus. Nat. Hist.

and that these glands, or others controlled by them, were in some
way responsible for an abnormal progress of molt, or for a re-
versal of molt in that one molt began before the previous molt
had been completed.

Excepting this one specimen, no. 783 from Vinton, Ohio, all of
those in transitional pelage indicate that the direction of the molt
pattern is the same as in M. frenata and M. erminea. That is to
say, the autumnal molt begins on the midventral line and the molt
in spring begins on the mid-dorsal line. Furthermore, the normal
progress of each molt appears to follow the same pattern that has
been described above for Mustela frenata.

A possible explanation of unseasonal molt in the southeastern
area of occurrence of the species Mustela rixosa, and a possible
explanation of the abnormal molt of the female from Vinton, Ohio,
is that the species has only relatively recently invaded the area, and
has had insufficient time to adjust the physiology of its molting
mechanism to the longer periods of daylight that obtain later in
autumn and earher in spring than farther north. In the other two
species of American weasels, the change in length of periods of
light, it will be recalled, is known to indirectly control both molt
and some changes in the sexual cycle. Wright (1942B:109) has
shown that molt in spring precedes by one or two months the birth
of young in M. frenata, that the two phenomena are correlated in
a way that is statistically significant, and recognizes that progres-
sively longer periods of dayhght may be the causal stimulus. The
suggestion made above that M. rixosa does not hve in New England
or in the Rocky Mountains of the western United States because
each of the two areas already is inhabited by weasels of almost
equally small size, is in Hne with the idea that rixosa is a recent
immigrant to America, or more precisely that rixosa arrived later
than erminea.

Natural History.— Habitat and Numbers.— Soper (1946:136)
recounts that near the junction of the Antler and Souris rivers, Mani-
toba, this species occurs "both in the river valleys and on the upper
prairies", and later (1948:55), with reference to the Grand Prairie
of the Peace River region of Alberta, writes that the least weasel
"inhabits both parklands and mixed wood forest environments."

At most times, wherever found, the least weasel is regarded as
rare. Not only mammalogists regard it as rare and as a desirable
catch, but Indians likewise value it, probably because of its rarity.
For example, Osgood (1901:69-70), who caught a female least

MUSTELA RIXOSA 173

weasel at Tyonek, Alaska, writes tliat: "The natives regard the cap-
ture of one of these rare animals as a piece of great good fortune.
One old Indian who frequently visited our cabin told us that his
brother who had caught one when a small boy had in consequence
become a Ijig chief; and he assured me that since I had caught
one I must surely be destined to become a man of great wealth
and power."

Swenk's (1926:313-330) account of the species in Clay County,
Nebraska, shows, however, that the animal was far more abundant
in 1916 and 1917 than subsequently and inferentially than it was
before 1916. Clearest proof of multiannual fluctuation is provided
by P. O. Fryklund's (Swanson and Fryklund, 1935:120-126) receipt
of weasels from Roseau County, Minnesota. From 1895 to 1932
he had approximately equal opportunity to receive least weasels
each year. Those which came to his attention were distributed by
years as follows: 1895-1927, 7 individuals in all; winter of 1927-28,
3 individuals; winter of 1928-29, 59 individuals; 1929-1930, 84 in-
dividuals; 1930-1935, 3 individuals. "These records indicate a very
definite increase in the abundance of least weasels in the Roseau
region [in] the two years from the autumn of 1928 to the spring
of 1930. Mr. Fryklund has handled 166 least weasels in his 40
years in Roseau County, and of these, 143 were taken in the two
years mentioned."

The maximum home range of the least weasel is two acres and
a weasel seldom travels farther than ten rods from its burrow ac-
cording to Polderboer (1942:146) who, in the period December 20,
1939, to January 2, 1940, studied four least weasels and one long-
tailed weasel on a 144 acre farm in Butler County, Iowa.

Behavior

Of the voice, Llewellyn (1942:441) records that his captive speci-
men taken in Virginia uttered a shrill shriek when seizing prey or
when teased. When excessively annoyed the weasel also emitted
musk.

The sense of smell is used in hunting as was witnessed by George
L. Fordyce; he observed a least weasel following the scent of a
Peromyscus and saw the least weasel overtake and kill the mouse
(Seton, 1929 (2):637).

At a nest in a clover stack, in Manitoba, Criddle (1947:69), on
December 27, 1946, found the least weasel "to have been rather
remiss in its sanitary habits as its pile of dung was almost, or quite,
touching the nest and only just to the side of its entrance." There
were 117 voids.

174 University of Kansas Publs., Mus. Nat. Hist.

Enemies

The great-horned owl, barn owl and long-tailed weasel are to be
counted as enemies since Nelson (1934:252) found the fur, skull
and other fragments of the skeleton of a least weasel in one of 26
pellets of the great-horned owl in Wisconsin; Handley (1949:431)
found the skull and other skeletal remains of a least weasel in one
of 22 pellets of the barn owl in Virginia; and Polderboer, Kuhn and
Hendrickson (1941), in Iowa, found the remains of a least weasel
in the den and scats of a Mustela frenata. A domestic cat in Michi-
gan killed a least weasel (Dearborn, 1932B:277).

Food

Mice are killed by the least weasel biting into the back of the
head and neck according to Allen (1940:460) who reported upon
the growth of five young, from Michigan, that he had in captivity.
He further states that a weasel was able to kill a mouse in 30 sec-
onds. One large Microtus introduced into the cage slept with a
weasel for several days and ate parts of the mice that the weasel
killed but then the weasel killed this mouse! Llewellyn (1942:
440-441), in writing of a captive from Virginia, says: "When a live
mouse was placed in the cage, the weasel sprang upon it almost
instantly. Grasping the mouse by the back of the head, the weasel
bit its victim through the skull several times in rapid succession
and held on witli its sharp teeth. The sound of the teeth piercing
the bone was distinctly audible at a distance of several feet. Dur-
ing this interval the weasel hugged the mouse closely with its fore
legs and pressed it firmly to its belly through a kicking motion of
the hind legs. The hold on the back of the head was not relinquished
until the mouse was dead. The killing took only a few seconds.
Upon releasing the mouse the weasel usually came to the front of
the cage and inspected the observer for an interval of several sec-
onds after which it returned to its prey and began its meal at once.
Sometimes the blood would be licked from the wound in the back
of the head or perhaps an ear would be chewed a bit and the blood
licked off, but never did the weasel 'cut the throat' of its prey and
'suck the blood.'

"The weasel ate the head and brain first, beginning at the back
of the head and working forward. Just before reaching the nose
the process was reversed and eating then proceeded from the base
of the skull toward the tail of the mouse. The tip of the nose,
maxilla with teeth, and the tail seemed to be the parts least pre-

MUSTELA RIXOSA 175

ferred; they were not eaten when an abundance of food was pres-
ent. At no time did the weasel place its front feet on the mouse
in an attempt to hold it. A second or third mouse was killed im-
mediately upon being placed in the cage even though the first one
had not been consumed. The weasel, however, usually returned
to the partially eaten mouse and finished it before starting on a
new one. Upon completing a meal, especially if the meal had
been particularly bloody, the weasel rubbed its chin on the bottom
of the cage, scooting along and appearing more snake-like than
normal. Whenever I attempted to remove a mouse, or partially
eaten one, from the cage, the weasel hung to the mouse tenaciously,
and often allowed itself to be Hfted up in this manner.

"In the six days that the weasel was kept in captivity it was fed
10 house mice having a total weight of 118 grams. As no food was
given on one day, the amount of food eaten is probably shghtly
below the actual capacity of the animal. Since the weasel weighed
only about 32 grams, the average amount of food eaten a day was
slightly in excess of one-half the weight of the animal."

Polderboer (1942:146-147) found in three dens, in Iowa, bits
of Reithrodontomys (harvest mice) and Peromyscus maniculatus
(deer mouse), and in the digestive tract of one least weasel there
was a bone fragment and a few hairs of a deer mouse. In the ac-
count, given beyond, of a nest, Griddle (1947:69) records the Penn-
sylvania meadow mouse (Microttis pennsylvanicus druminondi)
and the Gapper red-backed vole (Clethrionomys gapperi) as prey
at Treesbank, Manitoba. The same author, concerning the same
place, earlier (1926:199-200) wrote that in 1922 the meadow mouse,
Microtus minor, "went into winter quarters in great numbers and its
homes were well stocked with provisions. ... all went well
until the middle of February, 1923. Then, within a few days, each
was taken possession of by a least weasel ( Mustela rixosa ) and the
inhabitants were quickly destroyed. One dwelHng was occupied
by one of these weasels for about two weeks during which time I
observed that it had dragged several mice over the snow to its
temporary home. This residence was examined in April, and in it
were discovered six dead Microtus minor, one Evotomys, the head
of another, and at least six or eight remnants of small rodents in-
cluding Microtus drummondi, these last remains being chiefly in-
dicated by the hair-lined nest of the weasel.

"The homes of 27 other vole communities examined at this
time were all found to have been entered by weasels, the inhabit-

176 University of Kansas Publs., Mus. Nat. Hist.

ants having been killed and partly eaten. Moreover, the weasels
had made the homes temporary centers from which they raided
other rodent habitations in the vicinity. Thus from being an abmi-
dant animal this vole was reduced to insignificance in the course
of a few weeks, while all other kinds of mice had suffered severely
from the same enemy."

An instance of predation on Peromyscus, reveahng some of the
methods of capturing prey, is recounted by Seton (1929 (2):636-
637 ) who quotes a letter to him from George L. Fordyce, of Youngs-
town, Ohio, as follows: "While out in the field this morning (Dec.
26), walking along the bank of a ravine at the edge of our golf
course, I saw a Field-mouse run out of the bushes into the rough
grass that is just outside of the fair-green of the course. In another
instant, what I thought at first to be a white Mouse came out at
the same place. The Mouse ran into a wheel track, and disappeared
under the grass, coming out about 6 feet from where it went in.
The white animal followed through the same course, and when it
came out, I saw that it was a small Weasel, very little larger than
the Mouse, and that it was following the trail of the Mouse by
scent.

"For a time the Mouse ran in circles, and zigzagged about, often
. within 4 or 5 feet of the Weasel; but the latter seemed so
intent on the trail, that it did not notice the Mouse to one side. Af-
ter a time the latter started toward the open golf course; and when
the Weasel reached the point where the trail was straight, it sighted
the prey, made a sudden dash forward, and, although 25 feet be-
hind, overtook the Mouse while it was going 3 or 4 feet.

"For a few seconds, they seemed to fight, until the Weasel got
the Mouse by the throat, and started for the bushes, dragging the
body. When it came to within about three feet of me, I moved a
little to see what it would do. It dropped its victim, and ran into
the ravine. The Mouse had a drop of bright red blood in the center
of its white throat. I waited near by for 15 or 20 minutes, thinking
the Weasel might come back, but it did not show up again; even
an hour later, tlie Mouse had not been disturbed."

There are two suggestions, but no proof that I know of, in the
hterature that the least weasel eats insects. Abbott (1884:27-32-
1st ed., 1884) gives considerable information on the food (some
insects included ) of the 'little weasel" which he describes ( op. cit.;
27) as having "a little pointed tail of a uniform brown color". Al-
though this suggests Mustela rixosa, Abbott mentions on the next

MUSTELA RIXOSA 177

page (page 28) that a specimen of the smaller weasel measured
six and a half inches from the tip of the snout to the base of the
tail and that the tail itself measured two and a fourth inches to the
tip of the last caudal vertebra. These measurements indicate that
Miistela erminea was involved. Because of the uncertainty as to
the species of Mustela involved, Abbott's interesting data on food,
nest and behavior are not recorded in the present work. Seton
(1929 (2):636) says that of several least weasels brought to D.
Nicholson at Morden, Manitoba, most of them decayed so quickly
that they could not be saved as specimens. To Seton this indicated
that insects were an important part of the food of the weasels.

In summary: Least weasels are known to eat harvest mice, deer
mice, meadow mice and red-backed mice; it is suspected that they
eat also insects.

Reproduction

Polderboer (1948:296) has taken six specimens in "northeastern
Iowa [in] . . . January and December — all males in winter
pelage. None of these males showed signs of sexual activity; in
all, the testes were retracted and diminutive in size. ... A
male least weasel in brown pelage was taken November 17, 1945,
at Marion, Iowa. This specimen had large testes that had de-
scended into the scrotum. The testes, when removed, were about
the size of medium-sized garden peas. Microscopic examination
of the testes and the vasa deferentia showed mature sperms to be
present. . . ."

On July 1, 1917, in Clay County, Nebraska, a nest with four
young was found (Swenk, 1926:321). On July 29, 1939, an adult
and five young were plowed out of the ground in Allegan County,
Michigan; one of the two young males weighed 40.5 grams two
days after capture (Allen, 1940:459-460). On August 12, 1932, ten
young with the mother, were found in Roseau County, Minnesota
(Swanson and Fryklund, 1935:125). September appears to have
been the month of birth of a specimen, no. 8472 in the Carnegie
Museum, taken on November 24 in Pittsburgh, Pennsylvania. In
October, a young least weasel is recorded from Pennsylvania
(Winecoff, 1930:313). Early December was the time of birth of a
specimen, approximately 10 weeks old, no. 88077, University of
Michigan, taken on February 21 in Allegan County. On Decem-
ber 25, 1927, in Washington County, Pennsylvania, "five full-sized,
though young . . . animals were caught under the same pile
of com fodder" (Sutton, 1929:253). The first week of January

178 University of Kansas Publs., Mus. Nat. Hist.

seems to have been the time of birth of a juvenile, no. 88080, Uni-
versity of Michigan, taken in Livingston County, Michigan, on
March 27, 1943, since the specimen is approximately seven weeks
old. On January 15, 1929, in Washington County, Pennsylvania,
four young with the eyes yet unopened were obtained from a nest
(Sutton, 1929:254). On January 25, 1928, young, the eyes of which
may not yet have been open, were taken from a den in Washington
County, Pennsylvania, by WinecofiF (1930:313), who records other
young having been taken in the same month as well as in Febru-
ary. On March 10, a female from North Portal, Saskatchewan, gave
buth to four young (Dunk, 1946:392). On April 18, 1916, four
young, half grown, were taken in Nebraska (Swenk, 1926:317).
On April 2, 1929, three young were found in Roseau County, Min-
nesota, according to Swanson and Fryklund (1935:125) who re-
mark that: "The Pennsylvania and Minnesota records show that
least weasels may be bom any time from July to early February in
the northern states." Now, with all of the above records available,
it turns out that November, May and June are the only months in
which young least weasels have not been reported. Of course some
of the young, for which the ages were not specified, were bom in
preceding months. Even so, the data now available suggests that,
in the United States, young least weasels may be born in every
month of the year. The number per htter is 3, 4, 4, 4, 5, 5, and 10,
yielding an average of 5.

The rate of growth of the young has not been studied enough to
allow of judging if it diflFers significantly from that of other species
of the genus. Allen (1940:459-460), however, tells us that of the
three young females and two young males captured on July 29,
1939, in Allegan County, Michigan, one male that was killed on
July 31, 1939, weighed 40.5 grams. The male remaining alive in-
creased from 46 grams (August 5) to 62.5 grams on September 20,
having eaten 63 mice while in captivity. The females in the period
of August 5 to September 4 increased in weight as follows: 41 up
to 49 grams; 44 to 50 grams; and 47 to 58 grams, having eaten, by
September 26, 60, 64 and 65 mice.

Concerning a nest in which young were found, Sutton (1929:
254) writes that on January 15, 1929, near Burgettstown, Washing-
ton County, Pennsylvania, an animal was seen to enter a small hole
in a creek bank. After the observer dug in a distance of approxi-
mately six inches an adult, female least weasel was seen and
obtained. Back of the animal, the hole, which turned sharply

MUSTELA RIXOSA 179

downward, was full of water. The weasel first seen was a female
nursing young. A chamber, to the side of the hole, filled with
dead grass, comprised a nest containing four young with the eyes
yet unopened. Several nests occupied by adult least weasels or by
least weasels that were old enough to shift for themselves have been
found. Polderboer ( 1942:145-147) in the winter of 1939-40, on a 144
acre farm in Butler County, Iowa, found four least weasels living,
singly, in burrows dug by moles and pocket gophers. The nests
therein made by mice were used by the least weasels. Winecoff
(1930:312-313) mentions one den in Pennsylvania that contained
the remains of only mice, "and not a hint of a feather." Above, in
the account of food of the least weasel. Griddle's (1926:199-200) ac-
count of the havoc wrought by least weasels among the meadow
mice (Microtus ochrogaster minor) has been given. In this ac-
count he mentions the fur-lined nests of the weasels that had
appropriated the homes of the Microtus. Griddle's (1947:69) later
account of a nest at Treesbank, Manitoba, is as follows: "A Nest
of the Least Weasel. — When a least weasel finds its way into
a locality that has a large number of mice in it, it selects for
its home one of their nests that has been made in a well concealed
place. This it immediately starts to improve by lining it with hair
plucked from its victims before eating them; and as long as
sufficient numbers of mice remain in the district the weasel con-
tinues adding their hair to the nest, so that the thickness of its
walls give one a good idea of the length of time it has been in use.
The nest is not only used for sleeping in, as most of the food
is consumed in it. Frozen mice are taken in to be thawed out and
the weasel carries those it has recently killed in to prevent them
getting frozen, or perhaps to have them warm for its next meal.

"On January 27, 1946, my son Percy called my attention to a
nest that he had just uncovered in a clover stack that we were
using. This nest had originally been made by a Drummond's vole,
Microtus pennsylvanicus drummondii, and taken from it by the
least weasel, Mustela rixosa, the tracks of which had been noticed
about the stack yard since the first snow in early November.

"The nest had evidently been in use for at least three months
and the continual additions made to its walls had been so great
that they were nearly an inch thick of hair matted together so
closely that it appeared to be felt. The hair alone weighed nearly
22 gm., so that with this for protection the weasel must have been
warm and comfortable through the severest winter weather.

180

University of Kansas Publs., Mus. Nat. Hist.

m^^m

M . r . c i I< i m o
2 t^Vi'-V'vAv'-y/.VI M . r . r I X o s a

• specimens examined

llllillillll III! M.r. compestri

leqheniensis

Fig. 28. Map showing occurrences and probable geographic ranges of the sub-
species of Mustela rixosa in North America.

MUSTELA RIXOSA 181

"In the nest were two red-backed mice, Clethrionomys gapperi,
one of which had the base of its skull eaten out. No hair had
been removed from either of them, but a Microtus lying in a side
tunnel some feet away had the long hair plucked from its back
and sides. In and close about the nest were found forty-three
front parts of mice skulls which had evidently been discarded be-
cause of the sharp teeth in the maxillaries. Seven full stomachs
and eleven hind feet of adult Microtus with parts of leg bones
were disclosed in, or under, the weasel's bed and a few small bits
of skin with hair attached were scattered among the plucked hair
of the nest.

"This weasel seems to have been rather remiss in its sanitary
habits as its pile of dung was almost, or quite, touching the nest
and only just to the side of its entrance. It was composed of 117
voids all of which contained much hair and broken bone,

"Six other mouse nests found in the same stack, or others ad-
joining it, had been thinly lined with hair. One of these had two
mice in it, a red-backed with its brain eaten out and a Microtus
with some hair plucked from its neck. Another nest contained the
front part of a skull with teeth and the hind feet and tail of a
red-back. Besides the mice found in the nests seven others were
discovered tucked away in side tunnels. One of these mice had
most of the hair plucked from its back. Whether all these mice
and nests belonged to the same weasel or not I am unable to
say, but it is usual for them to have several nests in the area
surrounding the one that is used as their headquarters or home."

Mustela rixosa eskimo (Stone)

Least Weasel

Plates 14 and 15

Putorius rixosus eskimo Stone, Proc. Acad. Nat. Sci. Philadelphia, 1900:44,

March 24, 1900.
Putorius (Gale) vulgaris, Coues, Fur-bearing animals, p. 102, 1877 (part).
Putorius rixosus Bangs, Proc. Biol. Soc. Washington, 10:21, February 25,

1896 (part); Merriam, N. Amer. Fauna, 11:14, June 30, 1896 (part).
Mustela rixosa eskimo. Miller, U. S. Nat. Mus. Bull., 79:96, December 31,

1912; Swenk, Joum. Mamm., 7:327, November 23, 1926; Hall, Univ.

Cahfomia Publ. Zool., 30:421, March 19, 1929.

Type. — Female, age in question, no. 848 in Acad. Nat. Sci. Philadelphia;
Point Barrow, Alaska; July 25, 1898; obtained by E. A. Mcllhenny. Type
not seen by me.

Range. — Alaska and Yukon Territory. See figure 28 on page 180.

Characters for ready recognition. — Differs from M. r. pygmaea of eastern
Asia in longer tail, averaging 11 rather than 16 per cent of length of head

182 University of Kansas Publs., Mus. Nat. Hist.

and body, and in study skins reaching only to heel instead of to point be-
tween heel and toes; from M. r. rixosa in shorter tail averaging 16 rather than
19 per cent of length of head and body and not extending beyond outstretched
hind feet in study skins; white of underparts extending dorsally as a reentrant
angle from upper lip to behind eye, rather than deUmited dorsally by a
boundary between white and brown color that extends straight across cheeks
from upper lip to side of body well below eye and ear; breadth of rostrum
measured across lacrimal processes more, instead of less, than 85.5 per cent
of orbitonasal length; from M. erminea of same region by basilar length of
skull less than 32; tail less than 50 and lacking black pencil.

Description. — Size. — Male: The original describer hsts measurements of
topotypes as follows: Total length, 204, 230; length of tail, 28, 31; length
of hind foot, 20, 22. Allowing 5 per cent for shrinkage, the hind feet of 5
topotypes yield an average measurement of 23 for the hind foot.

Female: Measurements of two topotypes are: Total length, 184, 180;
length of tail, 25, 25; length of hind foot, 24, 18. In four other topotypes
the hind feet, allowing 5 per cent for shrinkage, yield an average of 21.

Color. — Winter pelage all white, rarely with few white hairs in tip of tail
but no black pencil; summer pelage with upper parts about Raw Umber
and tone 3 of Chocolate pi. 343 of Oberthiir and Dauthenay; underparts
white, ex-tending over upper lip, insides of limbs and over all four feet. Line
of demarcation between underparts and upper parts extends from upper
Up posterodorsally to behind eye down to base of ear, up behind ear for
a third or more of its height, and back along side of body. Tail unicolor
all around and same color as upper parts. Least width of color of under-
parts averaging 83 per cent of greatest width of color of upper parts.

Skull. — Based on topotypes; see measurements and plates 14 and 15; weight,
0.82 (0.74-0.93) grams in males, and 0.80 and 0.84 in two females; basilar
length, 29.5 (27.6-30.1) in males and 27.8 (27.1-28.8) in females; other-
wise as described in M. e. richardsonii.

Remarks. — Among the earliest specimens preserved was one by
Edward W. Nelson in the course of his explorations of the Upper
Yukon, and one in 1874 by L. T. Turner from St. Michaels, Alaska.
Bangs, in 1896 (p. 22) mentioned the occurrence of the species
in Alaska, but it was not until 1900 (p. 44) that Stone named the
subspecies, and then principally on the basis of specimens obtained
two years before by E. A. Mcllhenny.

The large size, broad skull, light color and short tail are the
distinguishing subspecific characters of the race eskimo, and the
three characters first mentioned are distinguishing features also
of the subspecies of Mustela erminea, namely arctica, which in-
habits the same region. Possibly eskimo also will be found on
Banks Island and the other Arctic islands between Alaska and
Greenland, as is M. e. arctica; at the present time no specimens

MUSTELA RIXOSA 183

of Mustela rixosa are known from these islands although some race
of rixosa would be expected to occur there.

Animals from southern Alaska average slightly smaller than those
from northern Alaska, and this decrease in size toward the south
probably represents intergradation with M. r. rixosa. Further evi-
dence of intergradation is furnished by the short tail of the specimen
from 15 miles east of Atlin; in other particulars this specimen agrees
with the subspecies rixosa to which it is here referred. Neverthe-
less, the short tail, and color pattern, namely reentrant angle of
white behind the eye, is to be seen in all Alaskan specimens ex-
amined in the brown pelage, even in no. 107591, from Tyoonok
on Cook Inlet, which Osgood (1901:69) and Swenk (1926:323)
thought might not differ from the subspecies M. r. rixosa.

Each of four male topotypes, hardly subadult in age, probably
of a single litter, is much larger than any other specimen seen from
Point Barrow. The basilar length, for example, is 31.9 as against
29.5, and the weight of the skull (with lower jaws) is as much as
1.5 grams, as against 0.93 in the heaviest of the other males. Initial
examination of materials from Point Barrow raised the suspicion
that two distinct species were represented — rixosa and a larger
one possibly allied to M. nivalis of the Old World. Nevertheless,
further study almost completely allayed the suspicion because the
only difference discernable is one of size, and it is supposed that
additional specimens will bridge the gap in size and show that
M. r. eskimo at Point Barrow averages larger than the adult speci-
mens now available indicate. The four large males of subadult
age are nos. 42814-42816 and 42818 of the American Museum of
Natural History.

Of the fourteen adult and subadult skulls examined, two display

lesions resulting from infestation of the frontal sinuses by nematode

parasites. None of the young skulls show such infestation.

Specimens examined. — Total number, 42 as follows. Arranged alphabeti-
cally by Territory and District and unless otherwise indicated in the United
States National Museum.

Alaska. Barrow and Point Barrow, 19 {S\ T, 2\ V); Wainwright, 1'; Mts.
back of Icy Cape, V; west of Beechy Point, 1'; west edge of Colville River
Delta, 1'; Koyukuk River, 16 mi. above Beetles, 1; upper Yukon, 1; Fort Yukon,
1; Stephens Village, 1; Wales, 1"; McDonald Creek, tributary of Salcha Slough,
1; near head of Toklat River, 1; head of Kantishna River, 1; St. Michael, 4
(2'); Tyoonok [= Tyonek], 1; Bethel, 3; vie. Bristol Bay, 1.

Yukon. La Pierres House, 1; Klotassin River, tributary of White River, 1.

1. American Mus. Nat. History 4. Collection of W. E. Snyder

2. Mus. Vert. Zool., Univ. California 5. Colorado Museum of Nat\u-al History

3. Acad. Nat. Sciences of Philadelphia 6. Canadian National Museum

184 University of Kansas Publs., Mus. Nat. Hist.

Mustela rixosa rixosa (Bangs)

Least Weasel

Plates 14 and 15

Putorius rixosus Bangs, Proc. Biol. Soc. Washington, 10:21, pi. 1, fig. 6,
pi. 2, fig. 6, pi. 3, fig. 4, February 25, 1896; Merriam, N. Arner. Fauna,
11:14, pi. 2, figs. 7, 7a, June 30, 1896.

Putorius pusillus, Baird, Mamm. N. Amer., p. 159, 1858.

Putorius (Gale) vulgaris, Coues, Fur-bearing animals, p. 102, 1877.

Miustela]. rixosa, Thomas, Proc. Zobl. Soc. London, p. 168, March, 1911.

Mustela rixosa rixosa, Miller, U. S. Nat. Mus. Bull., 79:96, December 31,
1912; Swenk, Joum. Mamm., 7:327, November 23, 1926.

Type. — Female, adult, skin and skull; no. 642 Bangs Coll. in Mus. Comp.
Zool.; Osier, Saskatchewan; July 15, 1893; obtained by W. C. Colt; original
no. 79 according to describer.

The skull lacks the basioccipital, basisphenoid, and left zygomatic arch.
The "crowns" of the lower canines are missing; otherwise the teeth are present
and entire. The skin is fairly well made, with soles of hind feet up, in good
condition and in summer pelage.

Range. — From northern British Columbia and Great Slave Lake south on
the west side of the Rocky Mountains to Ootsa Lake, British Columbia, and
on the east side of the Rocky Mountains, south to central Montana, North
Dakota and Minnesota; eastward in Canada, entirely north of St. Lawrence
River, to Atlantic Ocean. See figure 28 on page 180.

Characters for ready recognition. — Difi^ers from M. r. eskimo in longer tail
averaging 19 rather than 16 per cent of length of head and body and extending
beyond outstretched hind feet in study skins, rather than to a point short of
tips of toes; boundary between brown upper parts and white underparts
extending straight across cheeks from upper fip to side of body well below
eye and ear, rather than with reentrant angle from upper lip carrying white
upward to point behind eye, and with breadth of rostrum less, instead of more,
than 85.5 per cent of orbitonasal length; from M. r. campestris by smaller size:
hind foot less than 25 in males and ordinarily less than 22 in females; in
males total length less than 216 and tail averaging less than 34, and in females
total length averaging less than 182 and tail averaging less than 29; color
said to average darker; from M. r. allegheniensis by three average differences,
namely lighter color, longer tympanic bullae and larger size of males; from
M. frenata and M. erminea of same region by basilar length of skull less than
32; tail less than 50, and lacking black pencil.

Description. — Size. — Male: Six adults and subadults from Shaunavon,
Saskatchewan, yield average and extreme measurements as follows: Total
length, 202 (188-208); length of tail, 32.5 (31.5-34.0); length of hind foot,
22.8 (21-24).

Female: One adult and 3 subadults from the same area yield average
and extreme measurements as follows: Total length, 172 (162-190.5); length
of tail, 27.4 (24-34); length of hind foot, 19.6 (17.5-22).

Color. — Winter pelage all white, rarely brown; as described in M. r. eskimo
except that fine of demarcation on side of head betwen upper parts and under-
parts passes almost straight back without the dorsally directed reentrant area

MUSTELA RIXOSA 185

of white behind the eye and ear; least width of color of underparts averaging
52 per cent of greatest width of color of upper parts.

Skull (Based on those from Shaunavon, Sask.) — Sec measurements and
plates 14 and 15; weight, 0.88 (0.70-0.98) grams in males and 0.55 (0.54-0.56)
in females; basilar length, 29.5 (28.4-30.4) in males and 26.1 (24.7-27.0)
in females; otherwise as described in M. e. richardsonii.

Remarks. — As early as 1858 (p. 159) Baird recognized an indi-
vidual of this race from Pembina, Minnesota, as pertaining to a
distinct species. Although he used for it tlie specific name pusilltis
originally proposed by DeKay for a small weasel from the state of
New York, Baird wisely noted that the specimen he described
"may be different from the New York species. . . ." After pre-
paring this account, Baird included a second specimen, from Fort
Steilacoom, Washington Territory, which he thought might be the
same, but the differences that he was careful to point out, in tlie
light of later knowledge, show it to be of the species Mustela er-
minea. Only a few other naturalists followed Baird in distinguish-
ing the least weasel as a separate species until Bangs in 1896 (p. 21 )
clearly differentiated it and proposed for it the name Putoritts rix-
osus, which continues in use today and applies to the species.

The accumulation at the National Museum of Canada, through
the energy of Dr. R. M. Anderson, of a good series of specimens
from Saskatchewan in the general vicinity of the type locality allows
for the first time an adequate conception of the amount of secondary
sexual variation and individual variation and permits recognition
of subspecific characters to differentiate between M. r. rixosa and
the subspecies eskimo and campestris. In comparison with the
subspecies allegheniensis the basis for segregation is less clear and
will remain somewhat in doubt until additional adults of allegheni-
ensis from, say, Pennsylvania, become available with accurate ex-
ternal measurements taken in the flesh and especially with com-
plete skulls.

Intergradation with the subspecies eskimo is suggested by the
short tail of the specimen from fifteen miles east of Atlin, British
Columbia; in other particulars that specimen, a skin-alone, agrees
with the subspecies rixosa. Intergradation with campestris is indi-
cated by increased size of some specimens from North Dakota,
and is suggested with allegheniensis by the color of specimens
from Wisconsin and Illinois. Three specimens from Winona
County, in southeastern Minnesota, unfortunately are skulls-alone
without external measurements. Also, two of these skulls are of
young animals. The one adult, unsexed, is from Crystal Springs.

186 University of Kansas Publs., Mus. Nat. Hist.

Selected cranial measurements are: basilar length, 28.5; length
of tympanic bulla, 10.9. These measurements accord with those of
males of the subspecies rixosa to which the specimens from Winona
County, therefore, are here assigned. The possibilities have not
been excluded, however, that the adult is an unusually large female
of the subspecies campestris or a male of allegheniensis that has
tympanic bullae longer than average for that subspecies.

Some hesitation is felt in assigning the specimens, 8 in all, from
eastern Canada to the subspecies rixosa. The skin-alone from
Eagle River and the skin, with part of the skull, from St. Michael
Bay, are in transitional pelage and are of no help in appraising
subspecific characters. The one adult specimen which does have
a complete skull is from an island south of the Comb Hills. This
animal in all respects agrees with selected individuals of M. r.
rixosa from Saskatchewan, but each of the five other skins in sum-
mer pelage has spots of dark browai color on the breast. Only
about one specimen in three of rixosa from Saskatchewan is simi-
larly marked. Furthermore, on some of the specimens from eastern
Canada the spots are larger than on any of the animals from
farther west. The greater frequency of brown spots on the breast,
the larger average size of these spots, and the darker average
coloration of the upper parts are suggestive of geographic variation,
the existence of which has to be proved by additional and more
complete specimens from eastern Canada. For the time being,
specimens from there are tentatively assigned to the race rixosa.

Of 56 subadult and adult skulls only 3 ( 1 North Dakota; 1 Cal-
gary, Alberta; and 1 Island S Comb Hills, Queb.) display lesions
resulting from infestation of the frontal sinuses by nematode para-
sites. None of the young skulls shows such infestation.

Specimens examined. — Total number, 87 as follows. Arranged alpha-
betically by provinces and states and within each from north to south. Unless
otherwise indicated, specimens are in the United States National Museum.

Alberta. Miette River, 1'; 5 mi. NW Camrose, 1'; Camrose, 2 (1\ T);
"near Camrose", 2'; Fks. Blindman and Red Deer rivers, 1^ Innisfail, 1*; Vet-
eran, V; Diddsbury [= Didsbury], 1; Calgary, 2 (1°, 1"); Shepard, 1\

British Columbia. Clarks Ranch, Halfway River, Peace River Dist., 1*; 15
mi. E Atlin, 1"; Wistaria, P. O., 3 {2\ V); Ootsa Lake, 1".

Labrador. Davis Inlet, 1^; 30 mi. upriver and 20 mi. toward Groswater Mts.,
Eagle River, 1; St. Michael Bay, 1.

Mackenzie. Old Fort Rehance, V; Fort Resolution, 2; Fort Smith, 1.

Manitoba. Gypsumville, 1*; Lake St. Martin Reserve, 1*.

Minnesota. Roseau County: Cedarbend, 2'; Grimstad, 1'; America, 2 (1',
1'°); Malung, 1^°; Norland, 1"; Falun, 3 ( 1', 1", 1"); Palmville, 1"; Spruce,
1"; Stokes, 1'". No locahty more definite than Marshall County, 1'. Clay Co.:
Moorhead, V. Winona County: "near" Whitman, 1"; Altura, 1"; Crystal
Springs, 1".

MUSTELA RIXOSA

187

Montana. Sun River Valley, 1; Wibaux in Wibaux County, 1.

North Dakota. Walsh Co.: Grafton, 15 (3', 1°, 5", 2\ 1", V\ 1"). Mc-
Henry County: 4 and 4M mi. N Upham, 2. Wells Co.: 1". Morton Co.:
Mandan, 1*.

Ontario. Algoma Dist.: Tatnall, near Oba, 1*. Moose Factory, 1".

Quebec. Island S of Comb Hills, James Bay, 1". Saguenay County: Na-
tashkwan, 1.

Saskatchewan. Osier, 1"; "near Regina," 1'; Dollard, 2'; Shaunavon (and
"near" and 1 ™. NE), 9'; Klintowel P. O. (about 15 mi. N of Eastend), 1';
Eastend and "near" Eastend, 2\

Mustela rixosa allegheniensis (Rhoads)

Least Weasel

Plates 14, 15 and 41

Putorius allegheniensis Rhoads, Proc. Acad. Nat. Sci. Philadelphia, 1900:

751, March 25, 1901.
Putorius rixosus allegheniensis, Cory, Mamm. Illinois and Wisconsin, p.

378, 1912.
Mustela allegheniensis. Miller, U. S. Nat. Mus. Bull., 79:96, December 31,

1912.
Mustela rixosa allegheniensis, Swenk, Joum. Mamm., 7:328, November

23, 1926.

Type. — Probably male adult, skin and skull, no. 6195, Acad. Nat. Sci.
Philadelphia; near Beallsville, Washington Co., Pa.; about 1885 or 1886;
obtained by Robert Hawkins.

Type not seen by me.

Range. — Wisconsin, northern Illinois, northern Indiana, Michigan, Ohio,
Pennsylvania east to Dauphin County and south in the mountains to north-
western North Carolina. See figure 28 on page 180.

Characters for ready recognition. — Distinguished from M. r. rixosa by
three average differences, namely, darker color, shorter tympanic bullae, and
smaller size of males; from M. r. campestris in smaller size: hind foot less
than 25 in males and less than 22 in females; in males total length less than
216 and tail averaging less than 34, color averaging darker; from M. frenata
and M. erminea of same region by basilar length less than 31, tail less than
45, and lacking black pencil.

Description. — Size. — Male: An adult or subadult from Fair Oaks, Pa., a
subadult from Finleyville, Pa., and an adult from Huttonsville, W. Va.,
measure, respectively as follows: Total length, 206, 194, 191 (average 197);
length of tail, 37, 32, 28 (32); length of hind foot, 23 in each. An adult
from Roanoke, Indiana, weighs 40.6 grams.

1. Canadian National Museum 10.

2. Collection of Kenneth Racey 11.

3. Field Museum of Natural History 12.

4. Royal Ontario Museum of Zoology 13.

5. Univ. Kansas Mus. Nat. History 14.

6. American Mus. Nat. History 15.

7. Collection of Alex Walker 16.

8. California Academy of Sciences 17.

9. Provincial Museum of British Columbia 18.

Mus. Vert. Zool., Univ. California
Collection of Ralph Ellis
Collection of O. J. Murie
Acad. Nat. Sciences of Philadelphia
Museum of Zoology, Univ. Michigan
Museum of Comparative Zoology
Carnegie Museum
University of Minnesota
Collection of Mr. Green

188 University of Kansas Publs., Mus. Nat. Hist.

Female: Two young from Leasuresville, Pa., and Middle Paxton Twp.,
Pa., measure, respectively, as follows: Total length, 188, 172; length of
tail, 33, 30; length of hind foot, 20.5, 21. An adult from Monroeville, Ohio,
weighs 40.5 grams and a young individual from Middle Paxton Twp., Pa.,
39.3 grams, and a subadult from Swan Creek Exp. Station, Allegan Co.,
Mich., weighs 49 grams.

Color. — Winter pelage either all white, or brown as in summer; upper
parts about Raw Umber, or tone 2 of Carbo Brown of pi. 342 of Oberthiir
and Dauthenay. Underparts white at least on thoracic region; approxi-
mately three-fourths of specimens with brown rictal spot at angle of mouth
or with this area covered by brown upper parts which extend down on each
side and meet on the vmderparts in about one specimen out of three; upper
lips and hind feet ordinarily brown; toes of forefeet ordinarily white (see
under remarks for details of color pattern). Least width of color of under-
parts in the specimens in which the dark color of the upper parts does not
encircle the body averages 60 per cent of greatest width of color of upper
parts, or including all specimens the percentage is 42.

Skull (based on specimens from Pa. Hsted in table of cranial measurements,
which see and plates 14 and 15). — Basilar length 29.7 and 28.6 in male
and 28.0 in female; weights unavailable; otherwise as described in M. e. rich-
ardsonii. The length of the tympanic bullae seems to be actually less, and
less in relation to the basilar length, than in other American subspecies of
M. rixosa.

Remarks. — Robert Kennicott's mention in 1859 (p. 245) of what
seems to be this subspecies is the earhest reference to it that I
can identify in the hterature. He used the specific name pusillus
and it was not until 1900 that Samuel N. Rhoads proposed the
name Putorius allegheniensis. Since 1900, several records of
occurrence have been published which have made the geographic
range of this race better known.

An adequate number of specimens has been gathered only from
Ohio and from western Pennsylvania. Many from Ohio are with-
out accurate external measurements taken in the flesh. The ma-
jority of the specimens from Pennsylvania owe their preservation
to the willingness of local officials, who pay bounties on weasels,
to save the skins of Mustela rixosa. These specimens ordinarily
comprise the skin with locality but because the feet, external
measurements in the flesh, and skulls are unavailable, the material
is far from adequate and to give an accurate notion of the usual
or average cranial characters of allegheniensis in Pennsylvania,
skulls from there are especially desirable.

A smaller percentage of the specimens from Ohio than from Penn-
sylvania have the brown color of the upper parts meeting on the
underparts. Also, more of the specimens from Ohio are lighter

MUSTELA RIXOSA 189

colored and this suggests intergradation with the subspecies cam-
pestris and rixosa to the westward.

From Pennsylvania 23 animals in brown pelage are available. In
5 there is a rictal spot at the angle of the mouth; in 5 the area is
white and in 13 the brown color of the upper parts is continuous
over the area in question. Only 2 of 23 have the upper lips white.
Eight have the color of the upper parts meeting on the venter thus
restricting the white of the underparts to the chin, throat, and pec-
toral region, and 6 of these have a white area in the inguinal region
as well. The toes of the forefeet are white in 3 of 4 animals suit-
able for examination in this regard and the hind feet are marked
with white in 3 of the 8 animals which have the hind feet preserved.
Mustela rixosa in Pennsylvania parallels the species Mustela frenata
in that in this relatively humid area of the northeastern United
States the color of the upper parts is darker and the area of the
dark-colored upper parts is increased at the expense of the area of
the light-colored underparts. Also Mustela erminea in this same
region ( range of the subspecies Mustela cicognanii ) shows the same
tendency to darker color of upper parts and their extension in area at
the expense of the area of the light-colored underparts, or was men-
tioned above.

It is difficult to account for the seeming absence of the species
from New England and all that part of Canada and the United
States south of the St. Lawrence River and northeastward from
Pennsylvania. The size of females of M. erminea cicognanii in that
territory is so little more than in rixosa that the latter possibly can-
not successfully compete with the erminea stock which may already
occupy the ecologic niche to which rixosa is adapted. It will be
remembered that in western North America in territory seemingly
climatically suitable for rixosa it occurs no farther southward than
the line below which M. erminea has become reduced to a size
comparable with that of M. rixosa.

Of 41 subadult and adult skulls assigned to this subspecies 24
have obvious lesions in the frontal sinuses evidently resulting from
infestation by nematodes. More in detail, none of the specimens
from Illinois (3 individuals), Pennsylvania (3 barely subadult), or
West Virginia (2) displays lesions. From Wisconsin, Indiana, Vir-
ginia and North Carolina there is one specimen each and each
specimen displays lesions. From Ohio, 17 of 23 specimens dis-
play lesions. From Michigan 3 of 8 specimens display lesions; 2
adults and one subadult have lesions and 5 subadults do not have
lesions.

190 University of Kansas Publs., Mus. Nat. Hist.

Specimens examined. — Total number, 102 as follows: Arranged alpha-
betically by states and within each state by counties from north to south. Un-
less otherwise indicated, specimens are in the United States National Museum.

Indiana. Huntington Co.: Roanoke, 1. Wells County: Harrison Town-
ship, 1'.

Illinois. Lake Co.: Deeriield, 3'; no locahty more definite than county, 1'.
Cook Co.: Northfield, 1^ La Grange, 1'.

Michigan. Tuscola County: 8 mi. N Caro, 1\ Santilac County: Deckerville,
V. Allegan County: Swan Creek Exp. Station, 1*; Swan Creek Farm, 1';
T. 2N, R. 14W, 1'; Allegan, 1\ Livingston County: George Reserve, 1*;
J2 mi. N Unadilla, 1. Oakland County: Rochester, V. Macomb County:
Romeo, V. Wa.shtenaw County: 5 mi. SW Ann Arbor, 1'. Branch County:
vie. Coldwater, 1\

North Carolina, "near Marshall," 1.

Ohio. Northern part of state, 1*. Williams Co.: Stryker, l^ Lucas Co.:
Monclova, V. Erie Co.: Sandusky, 2'; marsh near Sandusky, 1'; Berlin Heights,
1'; no locality more definite than county, 1°. Wood Co.: 10 mi. NE Bowfing
Green, V; Bowling Green, 4'; 3 mi. E Bowling Green 1'; Plain Township, 1°;
Portage Townsliip, l^ Loraine County: Welfington, 1*. Huron County: west
of Monroeville, V. Summit County: Ira, 3*. Portage County: SufBeld, l\
Hancock County: Vanburen, 1^; Findlay, 1*; 9 mi. S Findlay, 1^ no locality
more definite than county, 7 (2^ 2*, 3°). Mahoning Co.: Ellsworth, 1. Craw-
ford County: "near Crestline", 1*. Delaware Co.: Sunbury, 1°; Lewis Center,
1*; no locality more definite than county, 1*. Licking Co.: Johnstown, 1°.
Fairfield County: Baltimore, 1*; Violet Township, 1*. Meigs [= Gallia?]
County: Vinton, 1*.

Pennsylvania. Erie County: McKeen Twp. 1. Crawford County: Spring-
boro, 1°; Pymatuning Swamp, between Hartstown and Shermansville, Sads-
bury Twp., 3'. Mercer County: Shenango Twp., 1. Lawrence County: Little
Beaver Twp., 1. Butler County: Leasuresville, 1'; Clearfield Twp., 1; Valencia,
1'. Armstrong County: Ford City, Burrell Twp., 1. Indiana County: Smicks-
burg, 1; N. Mahoning Twp., 2; White Twp., 1. Allegheny Co.: South Hills,
Pittsburgh, 1'; "near Pittsburgh", 1'; Fair Oaks, T. Westmoreland County:
Bolivar, 1. Dauphin County: Middle Paxton Twp., 1. Washington County:
Finleyville, 1; Rea, 5; Beallsville, 1°; Claysville, 1. Green Co.: Deep Valley,
1; Waynesburg, 1; Jefferson, 1; Cumberland Twp., 1. Fayette County: Acme,
1'; Somerset County, 1. Lancaster County, 1.

West Virginia. Randolph Co.: Huttonsville, 1.

Wisconsin. Sauk County: Sumpter Twp., 1". Dodge Co.: Beaver Dam, 1*.
Dane Co.: Madison, 1; McFarland (= MacFarland), 1.

Mustela rixosa campestris Jackson
Least Weasel

Plates 14 and 15

Mustela campestris Jackson, Proc. Biol. Soc. Washington, 26:124, May 21,

1913.
P[utorius]. pusillus, Aughey, Sketches of the physical geography and

geology of Nebraska, p. 119, 1880, Omaha.
Mustela rixosa campestris, Swenk, Joum. Mamm., 7:329, Nov. 23, 1926.

Type. — Female, adult, skin and skull; no. 171490, U. S. Nat. Mus., Biol.
Surv. Coll.; Beemer, Cuming County, Nebraska; April 18, 1911; obtained by
G. Sharp; x catalogue no. 8440.

1. Museum of Zoology, Univ. Michigan 5. American Mus. Nat. History

2. Field Museum of Natural History 6. Acad. Nat. Sciences of Philadelphia

3. Collection of E. J. Koestner 7. Carnegie Museum

4. Ohio State Museum 8. Collection of W. E. Snyder

MUSTELA RIXOSA 191

The skull is unbroken. On tlie left side, CI and P2 are missing; the other
teeth are present and entire. The skin is excellently made and in a good state
of preservation.

Range. — South Dakota, Nebraska and Iowa. See figure 28 on page 180.

Characters for ready recognition. — Differs from M. r. rixosa and M. r.
allegheniensis in larger size: Hind foot more than 25 in males and ordinarily
more than 22 in females; in males total length more than 216 and tail aver-
aging more than 34; color possibly slightly paler than in M. r. rixosa and
averaging paler than in M. r. allegheniensis; from M. frenata and M. erminea
of the same region by basilar length less than 32; tail less than 50, and lacking
black pencil.

Description. — Size. — Male: Four adults from Nebraska yield average and
extreme measurements as follows: Total length, 231 (225-237); length of tail,
36 (32-39); length of hind foot, 29 (28-31).

Female: Six adults from Nebraska yield average and extreme measurements
as follows: Total length, 192 (184-225); length of tail, 35 (28-40); length
of hind foot, 23 (20.5-26).

Color. — Winter pelage ordinarily white; as described in M. r. eskimo ex-
cept possibly paler and certainly with line of demarcation on side of head
between upper parts and underparts passing almost straight back without
the dorsally directed reentrant angles of white behind the eye and ear; least
width of color of underparts in four specimens from Nebraska averaging 80
(49-89) per cent of greatest width of color of upper parts, but in a fifth
animal in summer pelage the brown color of the upper parts encircles the
body.

Skull. — See measurements in table and plate 15; weight 1.1 grams (male
from Brown Co., S. D. ); basilar length, 30.7 in male from Clay Co., Neb., and
28.8 in female from same county; otherwise as described in M. e. richardsonii.

Remarks. — In his revisionary treatment of the American races of
Mustela rixosa, Myron H. Swenk (1926:313) credits Samuel Aughey
with recording this animal, M. r. campestris, from Nebraska, as early
as 1880, under the name Putorius pusillus. In 1908, Swenk recorded
the animal from the same state under the name rixosus and in 1913
the race campestris was formally named by H. H. T. Jackson.

On the testimony of a friend who had previously obtained several
specimens for him, Swenk (1926:321) records the least weasel
from Oshkosh, Garden County, Nebraska, which is a marginal
record of occurrence to the southwest for M. r. campestris.

At an early stage in the study of American weasels the writer
examined the specimens from Nebraska saved by Mr. Myron H.
Swenk and recorded measurements of them. However, at the time
of writing this account the specimens were not available for exami-
nation and the account of coloration is accordingly incomplete.

The large size, particularly the large external measurements,
comprises the principal distinguishing character of this subspecies
of the least weasel.

192 University of Kansas Publs., Mus. Nat. Hist.

Of the four adults examined from Iowa and South Dakota one
exhibits lesions such as result from infestation of the frontal sinuses
by nematodes.

Specimens examined. — Total number, 21 as follows. Arranged alphabeti-
cally by states and by counties, from north to south in each state. Unless other-
wise indicated, specimens are in the United States National Museum.

Iowa. Howard Co.: Chester, 1\ Palo Alto Co.: Emmetsburg, P. Kassuth
County: Algona, 1". Clayton Co.: National, 1. Storey County: Nevada, 1".
Wapello Co.: Ottumwa, V. Henry Co.: Mount Pleasant, 1'.

Nebraska. Holt County: Page, 1*. Madison County: Norfolk 1*. Cuming
Co.: Beemer, 1. Hamilton County: Chapman, 1*. Clay County: Inland to
1 mi. east thereof, 7*.

South Dakota. Brown County: shore of Sand Lake, S.15 T.126N, R.62W, 1.
Day County: Waubay Migratory Waterfowl Refuge, 1. McCook County:
Salem, T.

1. Coe College 4. Collection of Myron H. Swenk

2. Iowa State College 5. University of South Dakota

3. Iowa Wesleyan College

MUSTELA FRENATA 193

MU STELA FRENATA Lichtenstein

Long-tailed Weasel

(Synonymy under subspecies)

Type. — Mustela frenata Lichtenstein, DarstcUung neuer oder wenig be-
kannter Saugethiere, pi. 42 and corresponding text unpaged. 1832.

Range. — From southern Canada southward over all of the United States,
Mexico, Central America, Venezuela, and the republics of western South
America to southern Peru and extreme northern Bolivia. All the life-zones
from Alpine Arctic to Tropical are inhabited. In the extremely desert region
of southeastern California and western Arizona the species is scarce or possibly
absent although recovery of a skull (see under account of M. f. neomexicana)
from near the center of this region at Potholes on the Colorado River, and a
reported occurrence in the mountains of Baja California, Mexico, indicate that
a few individuals of the species live in favorable habitat even in this desert
region.

Characters for ready recognition. — Differs from Mustela erminea,
in regions where the two species occur together, by tail more than
44 per cent of length of head and body and by postglenoidal length
of skull less than 46 per cent of condylobasal length in males and
less than 48 per cent in females (see under characters of the spe-
cies); from Mustela rixosa by presence of black pencil on tail,
caudal vertebrae more than a fourth (%-%) of length of head
and body, basilar length of skull more than 34 mm.; from Mustela
africana by absence of thenar pad on forefoot, underparts without
longitudinal, median, abdominal stripe of same color as upper parts,
upper lips narrowly (rather than broadly) edged with color of
underparts, longest facial vibrissae extending to or behind posterior
margin of ear; presence of p2; more inflated (see pis. 23 and 30)
tympanic bullae.

Characters of the species. — Size large: Total length 300 to 550
mm.; tail two-fifths to seven-tenths of length of head and body, with
distinct black pencil at end; caudal vertebrae 19 to 23; skull with
long precranial portion; postglenoidal length, expressed as a per-
centage of the condylobasal length, less than 47 in females and ordi-
narily less than 46 in males; upper parts brown; light-colored under-
parts, in summer pelage, tinged with buffy or yellowish and continu-
ous from chin to inguinal region; some subspecies (southwestern
United States, Mexico, Central America, and Florida) with white or
yellowish facial markings which do not occur in any other Ameri-
can species of the genus Mustela.

7—3758

194 University of Kansas PxmLS., Mus. Nat. Hist.

Geographic variation.— Forty-two subspecies are recognized, and
the species is geographically more variable than any of the other
3 American species. Color, color-pattern especially on the head,
relative proportions of the tail, hind feet, body including the head,
and shape and size of the skull are the principal features in which
geographic variation has been noted. The variation in the skull
extends to the basicranial region ( shape and size of tympanic bullae
and related structures), interorbital region and preorbital region.

Natural History.— Rahitat and Numbers.— As has already been
remarked, the long-tailed weasel is absent from the extreme desert
of the southwestern United States and northwestern Mexico. Pos-
sibly the absence of water to drink is the limiting factor. In south-
em Nevada the finding of weasels only in places that were well
watered, even though small rodents suitable as food for weasels
were even more abundant in the surrounding desert, supports this
possibility that the absence of water to drink is the limiting factor.
Also at Berkeley, California, in early December of 1927 in the can-
yon at the head of Dwight Way and in the autumn and winter of
1928 in Strawberry Canyon on the campus of tlie University of
California, I trapped extensively for this species in different habitats
and obtained, in all, four individuals no one of which was farther
than 10 feet from water. The lesser cruising range of the individual
weasel than of, say, the coyote, probably explains why, in. an arid
region, for example Pahranagat Valley, Nevada, only the meadow
mice and their riparian associates are preyed upon by the long-
tailed weasel whereas the coyote preys upon these riparian rodents
and also upon the kangaroo rats and other rodents which are so
abundant in adjoining habitats that are devoid of water.

In areas where water is available every few hundred yards, no
particular habitat seems to be avoided in summer providing there
is food for the long-tailed weasel. In winter (January and March)
there obviously was a choice of habitat, possibly occasioned by more
abundant food or more satisfactory shelter, or both, in Centre
County, Pennsylvania, where Glover (1943B) found the popula-
tion density in the chestnut-oak habitat to be one weasel per 6.5
acres in areas of tree cuttings and slash and one weasel per 13.3
acres in the open forest. In the scrub oak-pitch pine forest type
the population was one weasel per 26.4 acres in tree cuttings and
slash and one weasel per 38.2 acres in tlie open forest. No weasel
was found in an area of 9.6 acres comprising a wood lot, the edge
of the forest, abandoned fence rows and an abandoned orchard.
The two types of forest in which he did find weasels, 25 in all,

MUSTELA FRENATA 195

comprised 381.6 acres. Glover's (op. cit.) data is the only precise
information known to me on actual numbers of long-tailed weasels
in a given area of any considerable size.

Fluctuations which I elsewhere (1946:57) have designated as
multiannual fluctuations occur in this species but seemingly not in
the degree that they do in Mustela erminea. This difference be-
tween the two species is to be expected because M. frenata does not
range so far northward toward the polar regions as does M. er-
minea and populations of most kinds of animals in the polar, at
least in the arctic, regions are subject to more extreme and more
regular fluctuations than are kinds of animals in temperate or
tropical regions. Indication of the means by which decrease in the
weasel population is brought about is afforded by Osgood's (1935:
156) observations around Rutland, Vermont. In the late winter
of 1934, tracks indicated that weasels left their usual haunts and
hunted cross lots, vainly trying to find food. Testing of the small
mammal population in the spring and summer of 1934 showed
that it was at low ebb. In the fall of 1934 mice and shrews were
abundant again but weasels seemed to be entirely absent. The
decrease in the population of weasels lagged behind the decrease
in the population of the herbivorous prey as did the subsequent in-
crease; this, of course, is the normal relation of carnivorous species
of mammals and their prey, at least in and above the Transition
Life-zone.

The average distance away from the central den which four
weasels (sex unspecified) traveled in a single night at Ames, Iowa,
was 312 feet; the maximum distance was 642 feet. These data
were obtained in the winter of 1939 by Polderboer, Kuhn and
Hendrickson (1941:115) who studied the tracks in the snow. In
Manitoba, Griddle and Griddle (1925:143) noted that a female
which lived in their basement often wandered more than half a mile
away in search of food. In Michigan, Quick (1944:75) found the
maximum distance traveled in one day ( = night? ) by a large male
to be 3.43 miles although two miles was the average distance
traveled by this individual. In 1942, from January 4 to March 4,
in Gentre Gounty, Pennsylvania, Glover (1943B) studied tracks of
11 males and 10 females, in newly fallen snow, and ascertained
that the distance traveled in a single night averaged 704 ( 60-2535 )
feet for the male and 346 ( 20-1420 ) feet for the female. The weasels
in the open timber traveled farther per trip than those in the
brushland and dense stands of trees.

196 University of Kansas Publs., Mus. Nat. Hist.

Behavior

An adult female (now the holotype of Mustela frenata neva-
densis) seen running across a field, and, I think, unaware of my
presence, at every bound bent her back up so far that she re-
minded me of a measuring worm. For part of the time when run-
ning, the tail was held ofiF the ground straight out behind, and
then, for a while, inclined upward at an angle of about 45°. An-
other weasel that I saw in the daytime, and that I think was un-
aware of my presence, was bounding along among the Baccharis
bushes on the south-facing slope of Dwight Way Canyon, Berkeley,
California. This individual, at each bound, arched the back up
so high as to remind me, again, of a measuring worm.

The long-tailed weasel is a land mammal and unlike its close
relative, the mink, is seldom seen in the water. That it can swim,
however, is attested by the capture of one while it was swimming
across the Rio Ramos in Mexico (Davis, 1944:381). Also, Green
(1936), in May, in Gratiot County, Michigan, saw a weasel, nm-
ning with a Peromyscus in its mouth. The weasel dropped tlie
mouse, entered the water and swam to a hole among stones.

More instances of climbing, than of swimming, have been re-
ported in the literature for the long-tailed weasel. Seton (1929
(2):625) quotes William M. GraflBus of Pennsylvania as having
seen a weasel closely pursue a red squirrel nearly to the topmost
branch of a large hemlock. When the squirrel loosed its hold and
dropped into a stream, the weasel descended to the ground and
caught and killed the squirrel when it emerged from the water.
Pearce (1937:483), in central New York State, on July 29, 1931,
watched a weasel chase a chipmunk up a black cherry tree ten
inches in diameter, and noted that the first rush carried the weasel
"straight up the trunk for approximately 10 feet, where it hesitated
momentarily before continuing. Then, instead of climbing verti-
cally, it made progress by traveling in short ascending spirals
around the trunk, scarcely making 3 feet in height for each circuit
of the tree. Upon reaching the limb by which the chipmunk
escaped, the weasel followed out along this in the same spiral
manner. This limb had a diameter of about 4 inches at its base and
extended upward at an angle of perhaps 20 degrees above the
horizontal. ... it made its way head first almost down to
the ground, using the same spiral mode of progress, but at a
leisurely pace . . . While traveling down the side limb it ap-
peared practically to wrap its sinuous body around the limb."

A male long-tailed weasel, from Colorado, which I kept captive

MUSTELA FRENATA 197

was often fed freshly killed mice. These I thrust through one of
the small openings in the wire mesh. The weasel quickly learned
to seize any part of a mouse tlius