Chapter I

Geographic Distribution and Taxonomy of the Chipmunks of Wyoming

By

JOHN A. WHITE

University of Kansas Publications

Museum of Natural History

Volume 5, No. 34, pp. 583-610, 3 figures in text

December 1, 1953

University of Kansas LAWRENCE 1953

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, A. Byron Leonard, and Robert W. Wilson

Volume 5, No. 34, pp. 583-610, 3 figures in text

December 1, 1953

UNIVERSITY OF KANSAS Lawrence, Kansas

PRINTED BY FERD VOILAND, JR., STATE PRINTER TOPEKA, KANSAS 1953

CONTENTS

PAGE

Purpose 586

Methods, Materials, and Acknowledgments 586

Variation 587
Juveniles 587
Young 587
Subadults 588
Adults 588
Old adults 588

Key to the Species of Chipmunks Inhabiting Wyoming 589

Accounts of Species and Subspecies 590
_Eutamias minimus_ 590
_E. m. minimus_ 591
_E. m. consobrinus_ 593
_E. m. pallidus_ 594
_E. m. confinis_ 596
_E. m. silvaticus_ 597
_E. m. operarius_ 598

_Eutamias amoenus_ 602
_E. a. luteiventris_ 602

_Eutamias dorsalis_ 603
_E. d. utahensis_ 604

_Eutamias umbrinus_ 606
_E. u. umbrinus_ 606
_E. u. fremonti_ 607
_E. u. montanus_ 608

Review and Conclusions 609

Literature Cited 610

FIGURES

Figure 1. Subspecies of _Eutamias minimus_ 590

Figure 2. _Eutamias amoenus_ and _Eutamias dorsalis_ 604

Figure 3. Subspecies of _Eutamias umbrinus_ 605

PURPOSE

The purpose of the following account is to: (1) Show what kinds of chipmunks occur in Wyoming; (2) point out the interrelationships between these kinds; and (3) account, where possible, for the present distribution of these animals in Wyoming.

METHODS, MATERIALS, AND ACKNOWLEDGMENTS

Capitalized color terms in the following accounts are of Ridgway,
"Color Standards and Color Nomenclature," Washington, D.C., 1912.

The measurements of the skull that were used in this study were
made as shown in White (1953:566, fig. 1). These are: Greatest
length of skull, zygomatic breadth, cranial breadth, length of
nasals, length of lower tooth-row, condylo-alveolar length of
mandible, and inner mandibular length.

Of the external measurements, only the total length and the length
of the tail are recorded in table 1. Some field collectors measured
the ear from the notch and others from the crown; most collectors
measured the length of the hindfoot to the nearest millimeter
rather than in tenths of a millimeter as would have been desirable.
Consequently, I decided against using the length of the ear and
hindfoot in this report.

When the word "significantly" is used in comparisons, it is meant
to show that there is a significant statistical difference between
two or more samples. Whenever eight or more specimens from one
locality were available, the mean, range, standard deviation,
standard error of the mean, and coefficient of variability were
calculated.

Only adult specimens were used in comparison. "Aging" of specimens
is discussed on page 587 of this paper.

The geographic range of each species and subspecies is not
described in writing, for, the localities are plotted on maps along
with the geographic range of each subspecies, and under "specimens
examined" the locality of each specimen or series of specimens is
listed.

In the synonymy of each subspecies there appears, first the first
usage of a name, second the first usage of the name combination now
employed, and third, pure synonyms.

A total of 757 specimens of chipmunks are listed as examined in the
course of preparing this report. Additional specimens were less
carefully examined in the Biological Surveys Collection in
Washington, D.C. Specimens used in my study, unless otherwise
specified, are in the Museum of Natural History, University of
Kansas. The symbols representing the collections containing
specimens studied are as follows:

BS--United States Biological Surveys Collection.
FC--Collection of James S. Findley.
MM--Museum of Zoology, University of Michigan.
NM--United States National Museum.
KU--Museum of Natural History, University of Kansas.

I am grateful to Professor E. Raymond Hall for guidance in my study
and thank Doctors Robert W. Wilson, E. Lendell Cockrum, Keith R.
Kelson, A. Byron Leonard, Rollin H. Baker, and others at the Museum
of Natural History and Department of Zoology, University of Kansas,
for encouragement and advice. My wife, Alice M. White, made the
illustrations and helped me in many ways.

For permission to borrow and to study specimens, I thank Dr. W. H.
Burt of the Museum of Zoology, University of Michigan, Miss Viola
S. Schantz of the United States Fish and Wildlife Service, Mr.
Colin C. Sanborn of the Chicago Natural History Museum, and Mr.
James S. Findley.

Assistance with field work is acknowledged from the Kansas
University Endowment Association, the National Science Foundation
and the United States Navy, Office of Naval Research, through
contract No. NR161 791.

VARIATION

Secondary sexual variation in chipmunks is small; the females are slightly larger than the males. This difference in size is so slight that it can be ignored when making taxonomic comparisons, for, large samples of males and females of like age and from the same locality were compared and were found statistically not to be significantly different. This is in agreement with Johnson (1943:70) and Hall (1946:329).

Variations of taxonomic worth are treated in the accounts of species and subspecies.

Individual variation is slight, for, the analyses of measurements of the skulls of series of specimens of like age, reveal markedly low coefficients of variability resembling those published by Larrison (1949).

The age-categories here recognized are based primarily on the structure of the skull.

_Juveniles._--Nasals proportionally shorter and more pointed anteriorly than in other categories; zygomatic arches more appressed to cranium; suture separating basisphenoid and presphenoid noticeably "open"; deciduous P4 and p4 show no wear through enamel; M3 and m3 not yet erupted; peglike deciduous P3 strongly leaning posteriorly; molars show no wear through enamel; parietals paperlike or thin; skull convex dorsally; 1 to 1-1/2 months of age.

_Young._--Nasals of adult proportions; zygomatic arches still noticeably appressed anteriorly to cranium; suture between basisphenoid and presphenoid still "open"; nasals rounded, no longer so pointed as in juveniles; deciduous P4 and p4 show wear through enamel layer, and in some specimens, permanent P4 and p4 can be seen beneath; roots of deciduous P4 and p4 clearly show erosion beneath; M3 and m3 fully erupted; peglike deciduous P3 still present; parietals noticeably thicker and less paperlike; skull flattened (not so convex dorsally), but not so flattened as in adults; 1-1/2 to 4 months of age.

In both juveniles and young the P4 and p4 are deciduous and differ in occlusal pattern from the permanent P4 and p4. In the deciduous P4 the anterior cingulum is projected strongly anteriorly forming the apex of the sharpest angle of a triangle, whereas the permanent P4 is trapezoidal in occlusal pattern. In the deciduous p4 the protoconid and metaconid are close together giving this tooth a triangular appearance in occlusal pattern, whereas this pattern in permanent p4 is trapezoidal (see Hall 1926:390).

_Subadults._--Adult configuration of skull reached; suture between basisphenoid and presphenoid completely closed; nasals rounded anteriorly; permanent P4 and p4 show no wear through enamel layer; wear through enamel layer of molars noticeable, especially through protocones; peglike permanent P3 slanting only slightly posteriorly; skull only slightly convex dorsally; parietals solid and resistant to pressure; lambdoidal crest weakly developed; 4 to 10 months of age.

_Adults._--Lambdoidal crest well developed; supraorbital ridges pronounced; P4 and p4 show wear through enamel layer and frequently as worn as molars; noticeable wear on lophs and lophids of molars; occlusal pattern always visible; ten months to 2 years of age.

_Old adults._--Ridges and crests extremely well developed; occlusal pattern of molariform teeth obliterated or nearly so; P3 noticeably worn; 2 to 4 years or older.

The hypohyal and ceratohyal bones of the hyoid apparatus are distinct from one another in juveniles and young, but are fused in subadults, adults, and old adults.

Lack of suitable material prevented me from studying chipmunks younger than juveniles. The patterns of growth of these younger chipmunks probably closely follow the changes described by Hall (1926) for _Citellus beecheyi_.

The tip of the baculum in juveniles and young is proportionally longer, in relation to the shaft, than in subadults, adults, and old adults.

Juvenal (juveniles and young) pelage in chipmunks is characterized by silkiness and sparseness, especially on the venter. The coloration of this juvenal pelage resembles that of adults in winter pelage which is duller than adult summer pelage. Adult pelage (subadults, adults, and old adults) is not so silky as juvenal pelage, but there are more hairs, especially on the venter. The color pattern is the same in both juvenal and adult pelages.

Chipmunks are born naked and blind and in about two weeks the "body is covered with silken hair clearly demonstrating the color pattern so characteristic of chipmunks...." (Shaw 1944:282). This "silken hair" is replaced by adult summer pelage, and juvenal chipmunks which are molting into adult summer pelage closely resemble the adult males, and later on in the summer, the adult females. Adult females molt later, as a rule, than adult males probably because of lactation. Summer molt begins, on chipmunks in Wyoming and South Dakota, in the latter part of June and is completed by the latter part of August or the first part of September.

Summer molt begins, topographically, in the region of the head and progresses posteriorly to the base of the tail, for, the tail does not molt into summer pelage. The winter molt starts at the same time at the tip of the tail and at the base of the tail, and from each place proceeds anteriorly. The sequence described above is the rule; exceptionally, there are some specimens which molted in patches. In most skins, molts are easily detected because distinct molt-lines were formed. The above description of molting is based on study of a large series of specimens of _Eutamias minimus silvaticus_ taken in several seasons of the year.

The summer pelage is bright, more especially on the sides. In late summer the pelage on the tail is markedly worn, and the hairs around its outer margin are broken. In texture, the summer pelage is not so soft as winter pelage, and this is probably owing to the presence of large amounts of "kinky" underfur in the winter pelage.

The winter pelage is soft, dull in color, and gives the specimen a grayish or an umbrous appearance. The guard hairs are longer than in the summer pelage.

KEY TO THE SPECIES OF THE CHIPMUNKS OF WYOMING

1. Dorsal stripes faint; general tone of upper parts grayish.
_Eutamias dorsalis_, p. 603

1'. Dorsal stripes distinct; general tone of upper parts tawny (not
grayish).

2. Venter yellowish or buff; tip of baculum more than 30 per
cent of length of shaft; shaft of baculum not widened at base.
_Eutamias amoenus_, p. 602

2'. Venter white; tip of baculum less than 29 per cent of
length of shaft--if more than 29 per cent, shaft widened at
base.

3. Size small to medium; greatest length of skull less
than 34 mm.; shaft of baculum not widened at base;
outermost dorsal dark stripe never obsolete _Eutamias
minimus_, p. 590

3'. Size large; greatest length of skull rarely less than
34 mm.; shaft of baculum widened at base; outermost dorsal
dark stripe often obsolete, never strongly evident.
_Eutamias umbrinus_, p. 606

ACCOUNTS OF SPECIES AND SUBSPECIES

Eutamias minimus (Bachman)

_Diagnosis._--Size small; tip of baculum of adults less than 28 per
cent of length of shaft; outermost dorsal dark stripes distinct;
skull small to medium; when skull medium, zygomatic breadth not
proportionally narrower.

_Comparisons._--From _Eutamias amoenus luteiventris_, the only
subspecies of that species in Wyoming, _E. minimus_ differs in:
Size smaller; tip of baculum in adults less than 28 per cent of
length of shaft; zygomatic arches proportionally wider; underparts
white or with less yellow or tawny.

From _E. umbrinus_, _E. minimus_ differs in: Size smaller; general
tone of upper parts lighter; base of baculum not widened but almost
as narrow as least diameter of shaft.

1. _E. m. minimus_
2. _E. m. consobrinus_
3. _E. m. pallidus_
4. _E. m. confinis_
5. _E. m. silvaticus_
6. _E. m. operarius_

From _E. dorsalis utahensis_, the only subspecies of this species in
Wyoming, _E. minimus_ differs in: Dorsal dark stripes distinct and
usually blackish; skull smaller; tip of baculum of adults less than
28 per cent of length of shaft.]

_Remarks._--This is the smallest of the species of chipmunks in Wyoming, and in the state can be readily distinguished from the other species by the smaller size and by the characteristic proportions of the baculum.

_E. minimus_ occurs in all the Life-zones of Wyoming, and inhabits open country, such as in the great expanses where sagebrush (_Artemesia_ sp.) is predominant, or inhabits the edges of forests, never occurring in the forest proper.

Analyses of measurements of the skull indicate that of the six subspecies of _E. minimus_ that are found in Wyoming, two are small (_E. m. minimus_ and _E. m. consobrinus_) and the other four are large (_E. m. pallidus_, _E. m. confinis_, _E. m. silvaticus_, and _E. m. operarius_). Within these size-groups the subspecies can be distinguished by differences in color pattern.

Eutamias minimus minimus (Bachman)

_Tamias minimus_ Bachman, Jour. Acad. Nat. Sci. Philadelphia, 8(pt.
1):71, 1839.

_Eutamias minimus_, Miller and Rehn, Proc. Boston Soc. Nat. Hist.,
30:42, December 27, 1901.

_Type._--Obtained on Green River, near mouth of Big Sandy Creek,
Sweetwater County, Wyoming. Age, sex, collector, and date when
obtained, not surely known.

_Diagnosis._--Size small; general tone of upper parts pale grayish
brown; baculum small.

_Description._--_Color pattern_: Crown Pinkish Buff mixed with
grayish white; facial stripes Snuff Brown mixed with black;
anterior margin of ear Drab washed with Cinnamon; hairs inside
posterior part of pinna Light Pinkish Cinnamon; posterior margin of
ear and postauricular patch grayish white; median dorsal dark
stripe black with Sayal Brown along margins; lateral pair of dark
stripes Sayal Brown more or less mixed with Fuscous; pairs of light
dorsal stripes grayish white and tinged with Buff; rump and thighs
Smoke Gray; dorsal surface of tail Fuscous Black mixed with
Cinnamon Buff; ventral surface of tail Sayal Brown or Clay Color,
Blackish Brown mixed with Cinnamon Buff around margins; antiplantar
and antipalmar surfaces of feet Pale Pinkish Buff; underparts
creamy white. _Skull_ and _Baculum_: Small but proportionally the
same as in other subspecies of _E. minimus_.

_Comparisons._--From _E. m. consobrinus_, the subspecies to the
west and south, _E. m. minimus_ differs in: Over-all tone of upper
parts lighter; underside of tail lighter.

From _E. m. pallidus_, the subspecies to the north and northeast,
_E. m. minimus_ differs in: Size smaller; skull shorter and
narrower; mandible shorter and shallower; baculum shorter; slightly
paler.

From _E. m. confinis_, the subspecies in the Big Horn Mountains,
_E. m. minimus_ differs in: Size smaller; skull shorter and
narrower; mandible shorter and shallower; baculum shorter; paler.

From _E. m. operarius_, the subspecies to the east and southeast,
_E. m. minimus_ differs in: Size smaller; skull shorter and
narrower; mandible shorter and shallower; baculum shorter; paler.

_Remarks._--_E. m. minimus_ is the smallest of the chipmunks that
occur in Wyoming. This pale little squirrel is found in the Red
Desert in Sweetwater County, where the features distinctive of the
subspecies are most strongly developed. Specimens from western
Sweetwater County and northwestern Uinta County are intergrades
between _E. m. minimus_ and _E. m. consobrinus_ and are referable
to _E. m. minimus_.

_Specimens examined._--Total number 167.

_Sublette Co._: 60 mi. SE Jackson [Teton County], 1 (MM); 2 mi. SE
Big Sandy, 1.

_Fremont Co._: 40 mi. E Dubois, 1; 12 mi. N and 3 mi. W Shoshoni,
4,650 ft., 2; 9 mi. N and 3 mi. E Shoshoni, 4,700 ft., 2; 7 mi. N
and 3 mi. E Shoshoni, 4,700 ft., 3; 2-1/2 mi. W Shoshoni, 4,800
ft., 1; Granite Mountains, 6; Mount Crooks, 8,600 ft., 6.

_Natrona Co._: 27 mi. N and 1 mi. E Powder River, 6,075 ft., 2; 15
mi. N and 1 mi. W Waltman, 1; 9 mi. S and 9 mi. W Waltman, 6,950
ft., 1; 16 mi. S and 11 mi. W Waltman, 6,950 ft., 2; Sun Ranch, 5
mi. W Independence Rock, 6,000 ft., 4; 9 mi. W and 1 mi. N
Independence Rock, 1; 5 mi. W and 1 mi. S Independence Rock, 2.

_Uinta Co._: 15 mi. WSW Granger [Sweetwater County], 1; 10 mi. SW
Granger [Sweetwater County], 10 (MM).

_Sweetwater Co._: Farson, 6,580 ft., 11; 5 mi. E Farson, 1; 27 mi.
N Table Rock, 1 (MM); 27 mi. N and 37 mi. E Rock Springs, 6,700
ft., 1; 25 mi. N and 38 mi. E Rock Springs, 6,700 ft., 3; Junction
of Big Sandy Creek and Green River, 6,400 ft., 7 (3MM); 17 mi. N
and 6 mi. W Rock Springs, 7,000 ft., 1; Thayer Junction, 9 (MM);
Table Rock, 1 (MM); Wamsutter, 1 (MM); Green River, 4 (MM); Bitter
Creek, 2 (FC); 13 mi. S and 14 mi. E Rock Springs, 6,650 ft., 2; 18
mi. S Bitter Creek, 6,800 ft., 2; 22 mi. SSW Bitter Creek, 5; 26
mi. S and 21 mi. W Rock Springs, 3; Kinney Ranch, 6,800 ft., 21 mi.
S Bitter Creek, 15; 30 mi. S Bitter Creek, 2; 32 mi. S and 22 mi. W
Rock Springs, 1; 32 mi. S and 22 mi. E Rock Springs, 7,025 ft., 12;
33 mi. S Bitter Creek, 6,900 ft., 6; 3 mi. W Green River, and 2 mi.
N Utah Boundary, 1; 1/2 mi. N Junction Henrys Fork and Utah
Boundary, 2; 1 mi. N Linwood, Utah, 1 (MM).

_Carbon Co._: 18 mi. NNE Sinclair, 6,500 ft., 2; Rawlins, 1; 30 mi.
E Rawlins, 6,750 ft., 2; Bridgers Pass, 18 mi. SW Rawlins, 7,500
ft., 1.

_Additional records_ (Howell 1929:38): _Lincoln Co._: Fontanelle;
Opal. _Sublette Co._: Big Piney; Green River at junction with New
Fork; Muddy Creek, near Big Sandy Creek. _Fremont Co._: Jackeys
Creek, 3 mi. S Dubois; Wind River near mouth of Meadow Creek; Ft.
Washakie; Green Mountains, 8 mi. E Rongis. _Natrona Co._: Bitter
Creek, near Powder River; Rattlesnake Mountains; Casper;
Independence Rock. _Sweetwater Co._: Eden, Steamboat Mountain;
Superior; Maxon; Green River, 4 mi. N Linwood, Utah; Henrys Fork,
at mouth of Burnt Fork. _Carbon Co._: Canyon Creek, 12 mi. S
Alcova; Ferris Mountains; Shirley; Shirley Mountains; 8-1/2 mi. SE
Lost Soldier [= Bairoil]; Ft. Steele; Sulphur Springs. _Albany
Co._: Spring Creek, 10 mi. W Marshall; Sheep Creek. _County
uncertain_: Little Sandy River; Green River.

Eutamias minimus consobrinus (J. A. Allen)

_Tamias minimus consobrinus_ J. A. Allen, Bull. Amer. Mus. Nat.
Hist. 3:112, June, 1890.

_Eutamias minimus consobrinus_, Miller and Rehn, Proc. Boston Soc.
Nat. Hist. 30:42, December 27, 1901.

_Eutamias lectus_ J. A. Allen, Brooklyn Inst. Mus. Sci. Bull.
1:117, March 31, 1905 (not in Wyoming), type from Beaver Valley,
Utah.

_Eutamias consobrinus clarus_ Bailey, Proc. Biol. Soc. Washington,
31:31, May 16, 1918, type from Swan Lake Valley, Yellowstone
National Park, Wyoming.

_Type._--Male, adult, skull and skin, No. 186456 (NM); from near
Barclay, Parley's Canyon, Wasatch Mountains, Salt Lake County,
Utah; obtained on October 31, 1888, by Vernon Bailey; original No.
361.

_Diagnosis._--Size small; over-all tone of upper parts grayish
brown; baculum small, as in _E. m. minimus_.

_Description._--_Color pattern_: Crown Smoke Gray mixed with
Ochraceous Tawny; upper facial stripe Fuscous; other facial stripes
Fuscous or Fuscous Black mixed with Tawny; hairs inside posterior
part of pinna Light Ochraceous Buff; anterior margin of ear
Ochraceous Tawny; posterior margin of ear and postauricular patch
grayish white; median dorsal dark stripe black with Ochraceous
Tawny along margins; other dorsal dark stripes black mixed with
Ochraceous Tawny; median pair of dorsal light stripes grayish white
with Ochraceous Tawny along margins; lateral pair of light dorsal
stripes white; sides Ochraceous Tawny or Light Sayal Brown; rump
and thighs Smoke Gray mixed with Cinnamon Buff; dorsal surface of
tail Fuscous Black mixed with Cinnamon Buff; ventral surface of
tail Sayal Brown, Fuscous Black along margin, and Cinnamon Buff or
Ochraceous Buff along outermost edge; antipalmar and antiplantar
surfaces of feet Light Pinkish Cinnamon or Pinkish Buff; underparts
grayish white mixed slightly with Buff. _Skull_ and _Baculum_:
Small but proportionally the same as in other subspecies of _E.
minimus_.

_Comparisons._--From _E. m. pallidus_, the subspecies to the east,
_E. m. consobrinus_ differs in: Color darker; size smaller; skull
narrower and shorter; baculum shorter.

From _E. m. confinis_, the subspecies from the Big Horn Mountains,
_E. m. consobrinus_ differs in: Over-all tone of upper parts less
grayish; underside of tail lighter; skull narrower and shorter;
baculum shorter.

For comparisons with _E. m. minimus_ see the account of that
subspecies.

_Remarks._--Specimens of this subspecies from the area between the Uinta Mountains and the mountains of the Wyoming and Wind River ranges, are clearly intergrades between _E. m. consobrinus_ and _E. m. minimus_ and are here referred to _E. m. consobrinus_. These specimens are paler than typical _E. m. consobrinus_ and considerably darker than _E. m. minimus_. These intergrades came from an area where the habitat is intermediate between that of _E. m. consobrinus_ and _E. m. minimus_ but more nearly like that of _E. m. consobrinus_.

_Specimens examined._--Total number, 135.

_Yellowstone Park_: Fishing Bridge, 1 (MM).

_Park Co._: SW slope Whirlwind Peak, 9,000 ft., 1.

_Teton Co._: N end Blacktail Butte, 6,600 ft., 1 mi. E Moose, 1;
Bar BC Ranch, 6,500 ft., 2-1/2 mi. NE Moose, 2; 3-3/4 mi. E Moose,
6,300 ft., 3; 3-3/4 mi. E and 3/4 mi. S Moran, 6,210 ft., 2; 5 mi.
S Moran, 1 (FC); 2 mi. S Elk Ranch, 2 (FC); 7 mi. S Moran, 1 (FC);
19 mi. E and 2 mi. S Moran, 1; Flat Creek Pass, 1 (MM); Flat
Creek-Crystal Creek Divide, 1 (MM); Flat Creek-Granite Creek
Divide, 5 (MM); Dry Hollow, Jackson, 1 (MM); Jackson, 4 (MM); Jenny
Lake, 2 (MM); Sheep Creek, Jackson, 1 (MM).

_Lincoln Co._: 3 mi. N and 11 mi. E Alpine, 5,650 ft., 2; 13 mi. N
and 2 mi. W Afton, 6,100 ft., 2; 10 mi. N and 2 mi. W Afton, 6,100
ft., 2; 6 mi. N and 2 mi. E Sage, 6,050 ft., 1; Kemmerer, 1;
Cumberland, 14 mi. S and 1 mi. W Kemmerer, 6,550 ft., 6.

_Sublette Co._: 5 mi. E and 9 mi. N Pinedale, 9,200 ft., 12; 10 mi.
NE Pinedale, 8,000 ft., 2; W end Half Moon Lake, 7,900 ft., 5; 3
mi. E and 5 mi. N Pinedale, 7,500 ft., 3; 2-1/4 mi. NE Pinedale,
7,500 ft, 3; 4 mi. W Pinedale, 7,200 ft., 2; 19 mi. W and 2 mi. S
Big Piney, 7,700 ft., 1; 31 mi. N Pinedale, 8,025 ft., 2.

_Fremont Co._: Togwotee Pass, 3 (1 FC); Moccasin Lake, 10,100 ft.,
19 mi. W and 4 mi. N Lander, 1; 16 mi. S and 5-1/2 mi. W Lander,
8,650 ft., 1; 23-1/2 mi. S and 5 mi. W Lander, 8,600 ft., 1; 3 mi.
E and 1/2 mi. N South Pass City, 7,900 ft., 7; Mosquito Park R.S.,
9,500 ft., 17-1/2 mi. W and 2-1/2 mi. N Lander, 1; 4 mi. S and
8-1/2 mi. W Lander, 9,200 ft., 1.

_Uinta Co._: 1/2 mi. S Cumberland [Lincoln County], 1; 2 mi. W Fort
Bridger, 6,070 ft., 1; 8-1/2 mi. W Fort Bridger, 6,700 ft., 17; 1/2
mi. S Mountain View, 6,900 ft., 2; 6 mi. S and 2-1/2 mi. E
Robertson, 8,200 ft., 3; 8 mi. S and 2-1/2 mi. E Robertson, 8,300
ft., 1; 9 mi. S Robertson, 8,000 ft., 5; 9-1/2 mi. S and 1 mi. W
Robertson, 8,600 ft., 2; 10 mi. S and 1 mi. W Robertson, 8,700 ft.,
4; 13 mi. S and 2 mi. E Robertson, 9,200 ft., 7; 2 mi. E and 12 mi.
S Robertson, Ashley Nat. For., 9,000 ft., 1; 11-1/2 mi. S and 2 mi.
E Robertson, 9,200 ft., 1; 4-1/2 mi. S and 4 mi. E Robertson, 8,025
ft., 1.

_Additional records_ (Howell 1929:48): _Yellowstone Park_: Bunsen
Peak; Swan Lake Valley; Canyon; Lake Station; Firehole River;
Summit Lake; Snow Pass. _Park Co._: Beartooth Lake; Whirlwind Peak,
near Pahaska Tepee; Valley; Needle Mountain. _Teton Co._: Elk,
Jackson Hole; Teton Pass. _Lincoln Co._: Thayne; head of La Barge
Creek; Smith Fork, 7,000 to 8,000 ft. _Sublette Co._: 12 mi. N
Kendall; Merna; Fremont Lake; Surveyor Park, 12 mi. NE Pinedale;
Bronx; Little Sandy Creek; Stanley; Big Sandy. _Fremont Co._: Lake
Fork, Wind River Mountains; Fremont Peak; South Pass City. _Uinta
Co._: Bear River Divide, 14 mi. N Evanstone; Evanstone; Ft.
Bridger; Spring Valley; Henry's Fork, 5 mi. W Lone Tree; Lone Tree;
Sage Creek (exact locality unknown).

Eutamias minimus pallidus (J. A. Allen)

_Tamias quadrivittatus b._ var. _pallidus_ J. A. Allen, Proc.
Boston Soc. Nat. Hist. 16:289, 1874.

_Eutamias minimus pallidus_, Howell, Jour. Mamm. 3:183, August 4,
1922.

_Lectotype._--Skull and skin, No. 11656/38311 (NM); from Camp
Thorne, near Glendive, Dawson County, Montana; obtained on July 18,
1873, by J. A. Allen; original No. 200.

_Diagnosis._--Size large; over-all tone of upper parts pale grayish
brown; baculum large.

_Description._--_Color pattern_: Crown Pale Smoke Gray mixed with
Clay Color; facial stripes Fuscous Black mixed with Clay Color;
anterior margin of ear and hairs inside posterior part of pinna
Pale Pinkish Buff; posterior margin of ear and postauricular patch
grayish white; median dorsal dark stripe black with Clay Color
along margins; other dorsal dark stripes Fuscous mixed with Clay
Color; median pair of dorsal light stripes Pale Smoke Gray; lateral
pair of dorsal light stripes creamy white; sides Cinnamon Buff;
rump and thighs Smoke Gray mixed with Pale Buff; dorsal surface of
tail Fuscous Black slightly mixed with Warm Buff; ventral surface
of tail Pinkish Cinnamon or Pinkish Buff, with Fuscous Black along
margin and Warm Buff along outermost edge; antipalmar and
antiplantar surfaces of feet Pinkish Buff, Warm Buff or Pale
Yellow-Orange; underparts white with dark underfur. _Skull_ and
_Baculum_: Large but of same proportions as in other subspecies of
_E. minimus_.

_Comparisons._--From _E. m. silvaticus_, the subspecies from the
Black Hills, _E. m. pallidus_ differs in: Paler; underside of tail
paler; sides paler.

From _E. m. confinis_, the subspecies from the Big Horn Mountains,
_E. m. pallidus_ differs in: Over-all tone of upper parts paler;
sides paler; underside of tail paler.

From _E. m. operarius_, the subspecies from the mountains in
south-central Wyoming, _E. m. pallidus_ differs in: Over-all tone
of upper parts paler; sides paler; underside of tail paler.

For comparisons with _E. m. minimus_ and _E. m. consobrinus_, see
the accounts of those subspecies.

_Remarks._--Specimens from near Buffalo, Johnson Co., are intergrades between _E. m. pallidus_ and _E. m. confinis_ and are referable to _E. m. confinis_. Specimens from near Sundance (not in Bear Lodge Mountains), Crook Co., are intergrades between _E. m. pallidus_ and _E. m. silvaticus_ (Howell 1929:55). Specimens from the Laramie Range in Converse Co. are intergrades between _E. m. pallidus_ and _E. m. operarius_, and referable to _E. m. operarius_. Specimens from near Greybull, Big Horn Co., are intergrades between _E. m. pallidus_ and _E. m. minimus_ and are referable to _E. m. pallidus_. These specimens show no intergradation with _E. m. confinis_ which occurs but a short distance to the east in the Big Horn Mountains. Intergradation between _E. m. pallidus_ and _E. m. minimus_ probably exists in northeastern Natrona Co. and southwestern Johnson Co.

Comparisons of specimens of _E. m. pallidus_ and _E. m. cacodemus_, indicates that, in my opinion, _E. m. cacodemus_ is entitled to subspecific recognition, for, the relationship between _E. m. pallidus_ to _E. m. cacodemus_ is the same as that between _E. m. pallidus_ and _E. m. confinis_.

_Specimens examined._--Total number, 58.

_Park Co._: 2 mi. S and 2 mi. E Meteetse, 5,750 ft., 3.

_Big Horn Co._: 6 mi. NW Greybull, 3,800 ft., 6; Greybull, 4 (BS);
7 mi. S Basin, 3,900 ft., 5.

_Sheridan Co._: 5 mi. NE Clearmont, 3,900 ft., 1.

_Campbell Co._: 5 mi. N and 8 mi. W Spotted Horse, 9; 6 mi. W and 4
mi. S Rockypoint, 4,200 ft., 1; 4 mi. S and 3 mi. W Rockypoint, 5;
Middle Butte, 6,010 ft., 38 mi. S and 19 mi. W Gillette, 3; South
Butte, 6,000 ft., 17-1/2 mi. W and 40-1/2 mi. S Gillette, 2; Ivy
Creek, 8 mi. W and 5 mi. N Spotted Horse, 6.

_Crook Co._: Moorcroft, Belle Fourche Valley, 8 (BS).

_Washakie Co._: 15 mi. W Tensleep, in badlands, 1 (BS); 8 mi. S and
8 mi. W Worland, 1; 10 mi. S Tensleep, near No Wood Creek, 2 (BS).

_Goshen Co._: Rawhide Buttes, 12 mi. S and 1 mi. W Lusk, 1.

_Laramie Co._: unspecified, 1.

_Additional records_ (Howell 1929:44): _Big Horn Co._: Otto;
Hyattville. _Sheridan Co._: Powder River at mouth of Clear Creek;
Sheridan; Arvada. _Weston Co._: Thornton; Upton; Pine Ridge;
Newcastle. _Hot Springs Co._: head of Bridger Creek; Willow Creek,
10 mi. SW Thermopolis. _Washakie Co._: 10 mi. S Manderson; Otter
Creek, Bighorn Basin. _Johnson Co._: Powder River Basin, near
Pumpkin Buttes. _Natrona Co._: Merino. _Converse Co._: Douglas.
_Platte Co._: Guernsey; 15 mi. SW Wheatland. _Goshen Co._: Rawhide
Butte. _Localities for which counties are unknown_: Owl Creek
Mountains; North Platte River.

Eutamias minimus confinis Howell

_Eutamias minimus confinis_ Howell, Jour. Mamm. 6:52, February 15,
1925.

_Type._--Female, adult, skull and skin No. 168957 (NM); from head
of Trapper Creek, west slope of Bighorn Mountains, Big Horn County,
Wyoming; obtained on July 7, 1910, by Merrit Cary; original No.
1956.

_Diagnosis._--Size large; over-all tone of upper parts grayish
brown; baculum large, as in _E. m. pallidus_.

_Description._--_Color pattern_: Crown Clay Color mixed with Pale
Smoke Gray; upper facial stripe Fuscous Black; other facial stripes
Fuscous Black slightly mixed with Tawny; anterior margin of ear
Yellow Ocher or Ochraceous-Orange; hairs inside posterior part of
pinna Yellow Ocher or Ochraceous-Orange; posterior margin of ear
Smoke Gray; postauricular patch buffy white or Smoke Gray; dorsal
dark stripes black or Fuscous Black more or less mixed with Tawny
or Tawny-Olive; dorsal light stripes creamy white, sometimes washed
with Pale Smoke Gray; sides Raw Sienna or Cinnamon Buff; rump and
thighs Pale Smoke Gray mixed with Tawny-Olive; dorsal surface of
tail black mixed with Clay Color; ventral surface of tail Clay
Color, black along margin and Light Buff or Light Ochraceous Buff
along outermost edge; antipalmar and antiplantar surfaces of feet
Pinkish Buff; underparts creamy white sometimes with grayish
underfur. _Skull_ and _Baculum_: Large but proportionally the same
as in other subspecies of _E. minimus_.

_Comparisons._--From _E. m. silvaticus_, the subspecies from the
Black Hills, _E. m. confinis_ differs in: General tone of upper
parts darker, more reddish and less grayish; ventral surface of
tail more tawny; skull and baculum of same size and proportions.

From _E. m. operarius_, the subspecies from the Laramie Range and
other mountains of south-central Wyoming, _E. m. confinis_ differs
in: Rump and thighs darker; sides darker; general tone of upper
parts more grayish.

For comparisons with _E. m. minimus_, _E. m. consobrinus_, and _E.
m. pallidus_, see the accounts of those subspecies.

_Remarks._--This subspecies is endemic to the Bighorn Mountains. Intergradation between _E. m. confinis_ and _E. m. minimus_ and between _E. m. pallidus_ and _E. m. confinis_ have already been discussed in the accounts of those subspecies.

_Specimens examined._--Total number, 85.

_Big Horn Co._: 12 mi. E and 2 mi. S Shell, 7,900 ft., 2; 13 mi. E
and 2 mi. N Shell, 8,500 ft., 2; 13 mi. E Shell, 8,300 ft., 1; 17
mi. E and 3 mi. S Shell, 9,000 ft., 8; 17-1/2 mi. E and 4-1/2 mi. S
Shell, 8,500 ft, 11; 19 mi. E and 4-1/2 mi. S Shell, 9,600 ft., 1;
9 mi. E and 9 mi. N Tensleep, 8,200 ft., 4.

_Sheridan Co._: Medicine Wheel Ranch, 9,000 ft., 28 mi. E Lovell,
11; 38 mi. E Lovell, Big Horn Nat. For., 9,600 ft., 10; 5-1/2 mi. W
and 1-1/2 mi. S Junction U.S. Highway 14 and Wyoming [State
Highway] 14, 8,480 ft., 2.

_Washakie Co._: 9 mi. E and 4 mi. N Tensleep, 7,000 ft., 26; 3 mi.
SE Tensleep, 4,300 ft., 1.

_Johnson Co._: 5-1/2 mi. W and 1 mi. S Buffalo, 6,500 ft., 4; 7-1/2
mi. W and 1 mi. S Buffalo, 6,500 ft., 2.

_Additional records_ (Howell 1929:46): _Sheridan Co._: 20 mi. from
Sheridan. _Washakie Co._: Head of Canyon Creek. _Johnson Co._: Head
of North Fork of Powder River.

Eutamias minimus silvaticus White

_Eutamias minimus silvaticus_ White, Univ. Kansas Publ. Mus. Nat.
Hist. 5 (19):259-262, April 10, 1952.

_Type._--Female, adult, skull and skin, No. 20050 (KU); from 3 mi.
NW Sundance, 5,900 ft., Crook County, Wyoming; obtained on July 4,
1947, by H. W. Setzer; original No. 1692.

_Diagnosis._--Size large; over-all tone of upper parts brownish
gray; sides Ochraceous Buff; baculum as in _E. m. pallidus_.

_Description._--_Color pattern_: Crown Sayal Brown washed with
Cinnamon Buff; facial stripes Fuscous Black mixed with Clay Color;
anterior margin of ear Ochraceous-Orange; hairs inside posterior
part of pinna Ochraceous Buff; posterior margin of ear and
postauricular patch grayish white; dorsal dark stripes Fuscous
Black more or less mixed with Ochraceous Buff; medial dorsal light
stripes Pale Smoke Gray with Ochraceous Buff along margins; lateral
dorsal light stripes grayish white or white with Ochraceous Buff
along margins; sides Ochraceous Buff; rump and thighs Smoke Gray
washed with Ochraceous Buff; dorsal surface of tail black
interspersed with Ochraceous Buff; ventral surface of tail
Ochraceous-Orange, with black along margin and Light Ochraceous
Buff along outermost edge; antipalmar and antiplantar surfaces of
feet Light Buff; underparts creamy white sometimes washed with
Ochraceous Buff. _Skull_ and _Baculum_: Large but of same
proportions as in other subspecies of _E. minimus_.

_Comparisons._--From _E. m. operarius_, the subspecies from
south-central Wyoming, _E. m. silvaticus_ differs in: Underside of
tail lighter; general tone of upper parts grayer; sides lighter;
skull and baculum of same size and proportions.

For comparisons with _E. m. pallidus_ and _E. m. confinis_, see the
accounts of those subspecies.

_Remarks._--Intergradation between _E. m. silvaticus_ and _E. m. pallidus_ has already been discussed under the account of _E. m. pallidus_.

_Specimens examined._--Total number, 42.

_Crook Co._: 15 mi. N Sundance, Black Hills Nat. Forest, 5,500 ft.,
6; 15 mi. ENE Sundance, 3,825 ft., 1; 3 mi. NW Sundance, 5,900 ft.,
14; 1 mi. N Sundance, Black Hills Nat. Forest, 1.

_Weston Co._: 1-1/2 mi. E Buckhorn, 6,150 ft., 19; SE Newcastle, 1
(MM).

_Additional records_ (Howell 1929:57): _Crook Co._: Devils Tower;
Sundance.

Eutamias minimus operarius Merriam

_Eutamias amoenus operarius_ Merriam, Proc. Biol. Soc. Washington,
18:164, June 29, 1905.

_Eutamias minimus operarius_, Howell, Jour. Mamm. 3:183, August 4,
1922.

_Type._--Female, adult, skull and skin, No. 129808 (BS); from Gold
Hill, 7,400 ft., Boulder County, Colorado; obtained on October 8,
1903, by Vernon Bailey; original No. 8160.

_Diagnosis._--Size large; general tone of upper parts dark reddish
brown; sides Tawny or Ochraceous Tawny; baculum large, as in _E. m.
pallidus_.

_Description._--_Color pattern_: Crown Cinnamon Buff mixed with
Pale Smoke Gray; facial stripes Fuscous Black mixed with Sayal
Brown; anterior margin of ear and hairs inside posterior part of
pinna Cinnamon Buff; posterior margin of ear and postauricular
patch Pale Smoke Gray; dorsal dark stripes black with Ochraceous
Tawny along margins; median dorsal light stripes Pale Smoke Gray
with Ochraceous Tawny along margins; lateral dorsal light stripes
white; sides Tawny or Ochraceous Tawny; rump and thighs Light
Grayish Olive; dorsal surface of tail Fuscous Black slightly mixed
with Clay Color; ventral surface of tail Sayal Brown or Ochraceous
Tawny with Fuscous Black along margin and Clay Color along
outermost edge; antipalmar and antiplantar surfaces of feet
Ochraceous Buff; underparts grayish white, often washed with Buff.
_Skull_ and _Baculum_: Large but of same proportions as in other
subspecies of _E. minimus_.

_Comparisons._--For comparisons with _E. m. minimus_, _E. m.
pallidus_, _E. m. confinis_, and _E. m. silvaticus_, see the
accounts of those subspecies.

_Remarks._--Specimens from the mountains near Savery in Carbon County and from near Medicine Bow Peak in Carbon and Albany counties are clearly referable to this race on the basis of color pattern. However, in the skull and baculum these specimens resemble _E. m. minimus_.

Specimens from the Laramie Range, 27 mi. N Laramie, show a color pattern which tends toward that of _E. m. pallidus_.

_Specimens examined._--Total number, 118.

_Natrona Co._: 2 mi. W and 7 mi. S Casper, 6,370 ft., 2; 10 mi. S
Casper, 7,750 ft., 3; 6 mi. S and 2 mi. W Casper, 5,900 ft., 1.

_Converse Co._: 21-1/2 mi. S and 24-1/2 mi. W Douglas, 7,600 ft.,
10.

_Carbon Co._: Lake Marie, 10,440 ft., 1; 2 mi. S and 1/2 mi. W
Medicine Bow Peak, 10,400 ft., 1; 2 mi. S and 2 mi. W Medicine Bow
Peak, 10,700 ft., 1; 10 mi. N and 14 mi. E Encampment, 8,000 ft.,
2; 8 mi. N and 14 mi. E Encampment, 8,400 ft., 2; 8 mi. N and 16
mi. E Encampment, 8,400 ft., 3; 21-1/2 mi. E and 8 mi. N
Encampment, 9,400 ft., 2; 10 mi. E and 6 mi. S Saratoga, 8,800 ft.,
1; 8 mi. N and 19-1/2 mi. E Savery, 8,800 ft., 16; 17 mi. E and 7
mi. N Savery, 8,300 ft., 1; 7 mi. N and 19 mi. E Savery, 10,128
ft., 1; 14 mi. E and 6 mi. N Savery, 8,400 ft., 1; 5 mi. N and 5
mi. E Savery, 6,900 ft., 2.

_Albany Co._: 27 mi. N and 7-1/2 mi. E Laramie, 6,960 ft., 12; 13
mi. E and 9 mi. N Laramie, 7,700 ft., 2; 8-3/4 mi. E and 6-1/2 mi.
S Laramie, 8,200 ft., 1; 5-1/2 mi. ESE Laramie, 8,500 ft., 1; 8 mi.
E and 4 mi. S Laramie, 8,600 ft, 1; 2 mi. SE Pole Mountain, 8,200
ft., 19; 3 mi. S Pole Mountain, 8,100 ft., 2; 1 mi. SSE Pole
Mountain, 8,350 ft., 3; 3 mi. ESE Browns Peak, 10,000 ft., 15;
2-1/2 mi. ESE Browns Peak, 10,300 ft., 1.

_Laramie Co._: 5 mi. W Horse Creek P.O., 7,200 ft., 2; 3-1/2 mi. W
Horse Creek P.O., 7,000 ft., 3; 2 mi. W Horse Creek P.O., 6,600
ft., 1.

_Additional records_ (Howell 1929:51): _Natrona Co._: Casper
Mountains, 7 mi. S Casper. _Carbon Co._: Bridger Peak; Riverside.
_Albany Co._: Springhill, 12 mi. N Laramie Peak; Eagle Peak; Bear
Creek, 3 mi. SW Eagle Peak; Laramie Mountains, 10 mi. E Laramie;
Woods [= Woods Landing]; Sherman. _Laramie Co._: Bluffs near Pole
Creek; 6 mi. W Islay.

TABLE 1

Average and Extreme Measurements in Millimeters of Adult Chipmunks that Occur in Wyoming

Table Legend:

Col. A: Greatest length of skull Col. B: Zygomatic breadth Col. C: Cranial breadth Col. D: Length of nasals Col. E: Total length Col. F: Length of tail Col. G: Length of lower tooth-row Col. H: Condylo-alveolar length of mandible

--------------+------+------+------+------+-----+-------+------+-------+
| A | B | C | D | E | F | G | H |
--------------+------+------+------+------+-----+-------+------+-------+
_E. m. minimus_, S of Bitter Creek, Sweetwater Co.

Mean (5) | 29.9 | 16.7 | 14.8 | 9.0 | 188 | 84.6 | 4.65 | 5.51 | Min. [Male] | 29.0 | 16.5 | 14.6 | 8.6 | 177 | 81.0 | 4.52 | 15.11 | Max. | 30.9 | 17.2 | 15.0 | 9.8 | 197 | 89.0 | 4.80 | 16.21 | | | | | | | | | | Mean (6) | 30.1 | 17.2 | 15.1 | 8.6 | 193 | 85.3 | 4.69 | 16.08 | Min. [Female] | 29.0 | 16.8 | 14.9 | 7.9 | 184 | 80.0 | 4.53 | 15.71 | Max. | 30.8 | 17.7 | 15.5 | 9.4 | 200 | 93.0 | 4.91 | 16.58 | --------------+------+------+------+------+-----+-------+------+-------+ _E. m. consobrinus_, near Jackson, Teton Co.

Mean (4) | 30.1 | 16.6 | 14.4 | 8.6 | 190 | 83.0 | 4.48 | 15.65 | Min. [Female] | 29.6 | 16.4 | 14.3 | 8.5 | 190 | 80.0 | 4.43 | 15.28 | Max. | 30.7 | 16.9 | 14.6 | 8.8 | 192 | 86.0 | 4.59 | 15.99 | | | | | | | | | | Mean (6) | 30.8 | 17.1 | 14.5 | 9.1 | 200 | 88.4 | 4.60 | 16.05 | Min. [Female] | 30.2 | 16.9 | 14.1 | 8.7 | 195 | 85.0 | 4.43 | 15.60 | Max. | 31.3 | 17.5 | 15.1 | 9.5 | 205 | 92.0 | 4.84 | 16.70 | --------------+------+------+------+------+-----+-------+------+-------+ _E. m. pallidus_, Moorcroft and Rockypoint, Weston Co.

Mean (9) | 31.8 | 18.0 | 15.3 | 9.3 | 193 | 85.8 | 4.84 | 16.74 | Min. [Male] | 31.4 | 17.7 | 14.9 | 8.5 | 185 | 80.0 | 4.34 | 16.23 | Max. | 32.5 | 18.7 | 15.9 | 9.7 | 204 | 91.0 | 5.02 | 17.21 | | | | | | | | | | Mean (7) | 32.2 | 18.2 | 15.5 | 9.6 | 205 | 91.0 | 4.97 | 17.02 | Min. [Female] | 31.4 | 17.8 | 15.1 | 9.1 | 203 | 86.0 | 4.70 | 16.30 | Max. | 32.9 | 18.9 | 16.0 | 10.3 | 214 | 99.0 | 5.18 | 17.39 | --------------+------+------+------+------+-----+-------+------+-------+ _E. m. confinis_, Bighorn Mts., near Tensleep, Washakie Co.

Mean (9) | 31.6 | 17.8 | 15.4 | 9.3 | 205 | 89.6 | 4.78 | 16.71 | Min. [Male] | 30.4 | 17.2 | 14.9 | 8.9 | 194 | 79.0 | 4.51 | 16.18 | Max. | 33.3 | 19.0 | 16.2 | 9.9 | 228 | 113.0 | 5.09 | 17.70 | | | | | | | | | | Mean (8) | 32.4 | 18.7 | 15.6 | 9.6 | 208 | 88.8 | 4.83 | 17.09 | Min. [Female] | 31.7 | 17.9 | 15.3 | 9.2 | 189 | 76.0 | 4.69 | 16.49 | Max. | 33.1 | 19.3 | 16.1 | 9.7 | 226 | 103.0 | 4.93 | 17.73 | --------------+------+------+------+------+-----+-------+------+-------+ _E. m. silvaticus_, 16 mi. N Custer, Pennington Co., S.D.

Mean (19) | 32.3 | 18.2 | 15.5 | 9.6 | 200 | 86.2 | 4.85 | 16.78 | Min. [Male] | 31.5 | 17.4 | 15.0 | 9.1 | 189 | 76.0 | 4.63 | 16.19 | Max. | 33.4 | 19.4 | 16.1 | 10.2 | 210 | 94.0 | 5.13 | 17.74 | | | | | | | | | | Mean (15) | 32.6 | 18.1 | 15.7 | 9.5 | 208 | 90.2 | 4.96 | 16.90 | Min. [Female] | 31.5 | 17.7 | 15.0 | 9.1 | 189 | 70.0 | 4.61 | 16.26 | Max. | 33.7 | 19.2 | 16.2 | 10.5 | 220 | 105.0 | 5.29 | 18.28 | --------------+------+------+------+------+-----+-------+------+-------+ _E. m. operarius_, near Pole Mt., Albany Co.

Mean (9) | 31.5 | 17.6 | 15.2 | 9.7 | 193 | 85.6 | 4.78 | 16.52 | Min. [Male] | 30.3 | 17.0 | 14.9 | 8.9 | 183 | 77.0 | 4.58 | 15.63 | Max. | 32.4 | 18.2 | 15.5 | 10.6 | 203 | 91.0 | 5.12 | 17.37 | | | | | | | | | | Mean (8) | 32.2 | 18.0 | 15.4 | 9.7 | 203 | 85.7 | 4.86 | 16.50 | Min. [Female] | 31.1 | 17.6 | 15.0 | 9.2 | 194 | 79.0 | 4.64 | 15.44 | Max. | 33.4 | 18.5 | 15.8 | 10.2 | 212 | 92.0 | 5.11 | 17.21 | --------------+------+------+------+------+-----+-------+------+-------+ _E. a. luteiventris_, near Moran, Teton Co.

Mean (20) | 33.6 | 18.2 | 15.5 | 10.6 | 212 | 94.8 | 5.14 | 17.27 | Min. [Male] | 32.2 | 17.4 | 14.9 | 9.8 | 198 | 87.0 | 4.86 | 16.42 | Max. | 35.2 | 18.7 | 16.2 | 12.1 | 221 | 108.0 | 5.37 | 18.39 | | | | | | | | | | Mean (10) | 33.8 | 18.5 | 15.5 | 11.1 | 217 | 91.7 | 5.13 | 17.47 | Min. [Female] | 33.4 | 18.1 | 15.1 | 10.5 | 203 | 81.0 | 5.06 | 16.89 | Max. | 34.7 | 19.0 | 16.0 | 11.5 | 225 | 100.0 | 5.32 | 18.33 | --------------+------+------+------+------+-----+-------+------+-------+ _E. d. utahensis_, W side Green River, 1 mi. N Utah border.

Mean (4) | 34.7 | 18.9 | 16.4 | 10.8 | 197 | 84.5 | 5.08 | 17.91 | Min. [Male] | 34.7 | 18.7 | 16.4 | 10.5 | 191 | 81.0 | 5.00 | 17.77 | Max. | 34.8 | 19.2 | 16.4 | 11.1 | 203 | 88.0 | 5.15 | 18.06 | | | | | | | | | | Mean (2) | 36.0 | 19.5 | 16.3 | 11.3 | 211 | 88.0 | 5.25 | 18.87 | Min. [Female] | 35.5 | 19.4 | 16.2 | 11.3 | 210 | 86.0 | 5.22 | 18.73 | Max. | 36.6 | 19.7 | 16.4 | 11.4 | 212 | 90.0 | 5.28 | 19.02 | --------------+------+------+------+------+-----+-------+------+-------+ _E. u. umbrinus_, Mts. S Robertson, Uinta Co.

Mean (11) | 34.7 | 18.9 | 15.7 | 10.9 | 218 | 96.2 | 5.13 | 18.04 | Min. [Male] | 34.3 | 18.3 | 15.6 | 10.3 | 215 | 81.0 | 4.79 | 17.57 | Max. | 35.2 | 19.4 | 16.0 | 11.7 | 228 | 112.0 | 5.42 | 18.59 | | | | | | | | | | Mean (4) | 35.1 | 19.2 | 15.9 | 11.0 | 224 | 96.4 | 5.17 | 18.46 | Min. [Female] | 34.9 | 19.2 | 15.7 | 10.3 | 204 | 90.0 | 5.11 | 18.31 | Max. | 35.4 | 20.0 | 16.2 | 11.8 | 234 | 100.0 | 5.22 | 18.98 | --------------+------+------+------+------+-----+-------+------+-------+ _E. u. fremonti_, Togwotee Pass, Fremont Co.

Mean (8) | 35.6 | 19.3 | 15.9 | 11.4 | 223 | 99.0 | 5.34 | 19.17 | Min. [Male] | 35.2 | 18.9 | 15.8 | 11.1 | 216 | 95.0 | 5.22 | 18.72 | Max. | 36.5 | 19.7 | 16.1 | 11.8 | 243 | 111.0 | 5.57 | 19.78 | | | | | | | | | | Mean (6) | 35.3 | 19.6 | 15.9 | 11.3 | 229 | 101.0 | 5.40 | 19.02 | Min. [Female] | 34.5 | 19.3 | 15.7 | 10.9 | 223 | 92.0 | 5.35 | 18.37 | Max. | 36.0 | 20.0 | 16.5 | 12.0 | 239 | 110.0 | 5.44 | 19.51 | --------------+------+------+------+------+-----+-------+------+-------+ _E. u. montanus_, near Longs Peak, Boulder Co., Colorado.

Mean (5) | 35.2 | 18.8 | 15.5 | 10.8 | 226 | 96.0 | 5.20 | 18.29 | Min. [Male] | 34.7 | 18.4 | 15.2 | 10.1 | 215 | 93.0 | 5.03 | 17.80 | Max. | 36.8 | 19.4 | 16.2 | 11.5 | 232 | 115.0 | 5.53 | 19.36 | | | | | | | | | | Mean (6) | 35.7 | 19.1 | 15.6 | 10.9 | 226 | 98.0 | 5.28 | 18.67 | Min. [Female] | 35.1 | 18.8 | 15.1 | 10.3 | 215 | 89.0 | 5.06 | 18.09 | Max. | 36.5 | 19.5 | 16.0 | 11.5 | 231 | 105.0 | 5.58 | 19.35 | --------------+------+------+------+------+-----+-------+------+-------+

Eutamias amoenus (J. A. Allen)

_Diagnosis._--Size medium; over-all tone of upper parts often
grayish olive; baculum small or medium, slender; tip of baculum 30
to 38 per cent of length of shaft; skull medium, narrow across
zygomata.

_Comparisons._--From _E. dorsalis utahensis_, the only subspecies
of this species in Wyoming, _E. amoenus luteiventris_ differs in:
Dorsal light and dark stripes distinct; over-all tone of upper
parts less grayish (more tawny); tip of baculum less than 38 per
cent of length of shaft in adult specimens.

From _E. umbrinus fremonti_, the only subspecies of this species
which occurs in the same area with _E. amoenus_ in Wyoming, _E. a.
luteiventris_ differs in: Smaller size; tawny underparts; base of
baculum not noticeably widened.

For comparisons with _E. minimus_ see the account of that species.

Eutamias amoenus luteiventris (J. A. Allen)

_Tamias quadrivittatus luteiventris_ J. A. Allen, Bull. Amer. Mus.
Nat. Hist., 3:101, June, 1890.

_Eutamias amoenus luteiventris_, Howell, Jour. Mamm., 3:183, August
4, 1922.

_Type._--Male, adult, skull and skin, No. 11991/37996 (NM); from
"Chief Mountain Lake" [Waterton Lake], 3-1/2 mi. N United
States-Canadian Boundary, Alberta; obtained on August 24, 1874, by
Elliot Coues; original No. 4596.

_Diagnosis._--General tone of upper parts ochraceous; underparts
strongly buffy; tip of baculum in adult specimens, more than 30 per
cent and less than 38 per cent of length of shaft.

_Description._--_Color pattern_: Crown Cinnamon mixed with Smoke
Gray; upper two facial stripes black; submalar stripe Fuscous or
Fuscous Black mixed with Ochraceous Tawny; anterior margin of ear
Ochraceous Tawny; posterior margin of ear and postauricular patch
Light Buff or buffy white; hairs inside posterior part of pinna
Ochraceous Tawny; median dorsal dark stripe black; lateral pair of
dorsal dark stripes black and mixed with Tawny, frequently
brownish; median pair of dorsal light stripes white tinged with
Pale Smoke Gray; lateral pair of dorsal light stripes creamy white;
sides Tawny or Ochraceous Tawny; rump and thighs Dark Smoke Gray
strongly mixed with Cinnamon Buff; dorsal surface of tail Fuscous
Black mixed with Clay Color; ventral surface of tail Light
Ochraceous Tawny, with Fuscous Black around margin and Clay Color
around outermost edge; antipalmar and antiplantar surfaces of feet
Cinnamon or Cinnamon Buff; underparts Cinnamon Buff or Light
Ochraceous Buff. _Skull_: Size medium; moderately narrowed across
zygomata. _Baculum_: Slender; not noticeably broadened at base; tip
more than 30 per cent of length of shaft.

_Remarks._--Although there are no records of this subspecies from the Wind River Mountains, it probably occurs there.

The niche that this subspecies occupies is similar to that of _E. m. consobrinus_ as shown by the fact that these two subspecies have been taken together at the same places.

Specimens of _E. a. luteiventris_ and _E. umbrinus fremonti_ have been taken together at the same places.

In general, _E. m. consobrinus_ occurs in open country and at the edges of forests, whereas _E. u. fremonti_ occurs in the forest. _E. a. luteiventris_ occurs in the intermediate habitat, that is to say, not far into the forest, and not so far out into the open as _E. m. consobrinus_.

_Specimens examined._--Total number, 83.

_Yellowstone Park_: Unspecified, 2.

_Park Co._: 31-1/2 mi. N and 36 mi. W Cody, 6,900 ft., 6; 29 mi. N
and 31 mi. W Cody, 7,200 ft., 1; 28 mi. N and 30 mi. W Cody, 7,200
ft., 1; 16-1/4 mi. N and 17 mi. W Cody, 5,625 ft., 3; 25 mi. S and
28 mi. W Cody, 6,350 ft., 2.

_Teton Co._: Two Ocean Lake, 2 (1 FC); Whetstone Creek, 8 (MM);
Emma Matilda Lake, 1 (FC); Pacific Creek Road, 2-1/2 mi. E Moran, 1
(FC); Two Ocean Lake Road, 2 (FC); 2 mi. E Moran, 1 (FC); 2-1/2 mi.
E and 1/4 mi. N Moran, 6,230 ft., 8; Pacific Creek, 1 (MM);
junction of Two Ocean Lake Road and U.S. Highway 187, 2 (FC);
Signal Mountain Road, 1 (FC); Leigh Lake, 9 (MM); Indian Paint
Brush Canyon, Teton Park, 1 (MM); Teton National Park, 3; 3 mi. E
and 1/4 mi. S Moran, 6,200 ft., 1; 3-3/4 mi. E and 1 mi. S Moran,
6,200 ft., 8; 2-1/2 mi. N and 3-1/2 mi. E Moran, 7,225 ft., 1;
Timbered Island, 6,750 ft., 4 mi. N Moose, 5; Bar BC Ranch, 6,500
ft., 2-1/2 mi. NE Moose, 9; Grand Teton, 9,000 ft., Teton Park, 1
(MM); Upper Arizona Creek, Jackson, 1 (MM).

_Lincoln Co._: 3 mi. N and 11 mi. E Alpine, 5,650 ft., 2.

_Additional records_ (Howell 1929:69): _Yellowstone Park_: Mammoth
Hot Springs; Roaring Mountain; Bunsen Peak; Yancey; Apollinaris
Spring; Canyon; Yellowstone Lake; Upper Geyser Basin; Old Faithful.
_Park Co._: Near head of Clarks Fork; Pahaska, N Fork Shoshone
River at Grinnell Creek; Valley. _Teton Co._: Moran; Teton
Mountains; Teton Pass. _Lincoln Co._: Afton, Salt River Mountains;
head of La Barge Creek, 9,100 ft.; Salt River Mountains, 10 mi. SE
Afton. _Sublette Co._: Merna; Stanley.

Eutamias dorsalis (Baird)

_Diagnosis._--Size medium to large; general tone of upper parts
Smoke Gray; dorsal stripes indistinct or obsolete; often brightly
colored at base of tail; keel of baculum proportionally high,
approximately 1/3 of length of tip; skull longer than 34.5 mm.

_Comparisons._--From _E. umbrinus_, _E. dorsalis_ differs in:
Dorsal stripes faint; skull smaller; base of baculum not noticeably
expanded; general tone of upper parts grayer.

For comparisons with _E. minimus_ and _E. amoenus_ see the accounts
of those species.

1. _E. amoenus luteiventris_
2. _E. dorsalis utahensis_]

Eutamias dorsalis utahensis Merriam

_Eutamias dorsalis utahensis_ Merriam, Proc. Biol. Soc. Washington,
11:210, July 1, 1897.

_Type._--Male, adult, skull and skin, No. 186457 (NM); from Ogden,
Weber County, Utah; obtained on October 9, 1888, by Vernon Bailey;
original No. 289.

_Diagnosis._--Size medium; dorsal stripes faint; baculum not
noticeably widened at base.

_Description._--_Color pattern_: Crown Pale Smoke Gray mixed with
Cinnamon; upper facial stripe Fuscous; other facial stripes Sayal
Brown mixed with Fuscous or Fuscous Black; anterior margin of ear
Ochraceous Tawny; posterior margin of ear and postauricular patch
grayish white; median dorsal dark stripe Fuscous or black; other
dorsal dark stripes black and mixed with gray, sometimes barely
discernible; dorsal pair light stripes Smoke Gray; lateral pair of
light stripes creamy white; rump and thighs Pale Smoke Gray mixed
with Cinnamon; dorsal surface of tail Fuscous Black mixed with
Tilleul Buff; underside of tail Cinnamon Buff or Pinkish Buff,
Fuscous Black around margin and Tilleul Buff around outermost edge;
antipalmar and antiplantar surfaces of feet Cinnamon Buff;
underparts creamy white; sides Pinkish Cinnamon or Light Pinkish
Cinnamon. _Skull_: Size medium; braincase well inflated; zygomata
strong, moderately appressed to cranium. _Baculum_: Small; keel
approximately 1/3 of length of tip.

_Remarks._--Only a few specimens of this subspecies have ever been taken in Wyoming. Little is known about the habits of this chipmunk, which normally is shy and wary.

_Specimens examined._--Total number, 6.

_Sweetwater Co._: W side Green River, 1 mi. N Utah border, 6.

_Additional records_ (Howell 1929:134): _Sweetwater Co._: Green
River, 4 mi. NE Linwood, Utah.

1. _E. u. umbrinus_
2. _E. u. fremonti_
3. _E. u. montanus_]

Eutamias umbrinus (J. A. Allen)

_Diagnosis._--Size large; general tone of upper parts dark; base of
baculum widened; outermost dorsal dark stripe barely discernible or
lacking; skull rarely shorter than 34.0 mm.

_Comparisons._--For comparisons with the other species of
_Eutamias_ in Wyoming, see the accounts of _E. minimus_, _E.
amoenus_, and _E. dorsalis_.

_Remarks._--_E. umbrinus_ is the largest of the species of _Eutamias_ occurring in Wyoming. This species usually occurs in the Canadian and Hudsonian life-zones in the mountains of northwestern, southwestern, and south-central Wyoming.

Eutamias umbrinus umbrinus (J. A. Allen)

_Tamias umbrinus_ J. A. Allen, Bull. Amer. Mus. Nat. Hist. 3:96,
June, 1890.

_Eutamias umbrinus_, Miller and Rehn, Proc. Boston Soc. Nat. Hist.,
30:45, December 27, 1901.

_Type._--Male, adult, skull and skin, No. 186463 (NM); from Blacks
Fork, about 9,500 ft., Uinta Mountains, Summit County, Utah;
obtained on September 19, 1888, by Vernon Bailey; original No. 228.

_Diagnosis._--Size medium; over-all tone of upper parts dark and
shadowy; skull smallest of this species in Wyoming.

_Description._--_Color pattern_: Crown Pale Smoke Gray; facial
stripes Fuscous Black or Snuff-Brown; ears Fuscous Black; posterior
margin of ear and postauricular patch grayish white; median dorsal
dark stripe black with Sayal Brown along margins; lateral pair of
dorsal dark stripes Fuscous Black mixed with Sayal Brown, or
entirely Sayal Brown; outermost pair of dorsal dark stripes Sayal
Brown mixed with Fuscous Black or lacking; sides Sayal Brown mixed
with Cinnamon; rump and thighs Sayal Brown mixed with Smoke Gray;
antipalmar and antiplantar surfaces of feet Cinnamon Buff;
underside of tail Ochraceous Tawny or Sayal Brown, with Fuscous
Black around margin and Pinkish Buff around outermost edge;
underparts creamy white with dark gray underfur. _Skull_: Smooth
and rounded; braincase inflated; zygomata strong. _Baculum_:
Broadened at base; shaft tapers rapidly to tip.

_Comparisons._--From _E. u. fremonti_, the subspecies from the
north in the mountains of northwestern Wyoming, _E. u. umbrinus_
differs in: Over-all tone of upper parts darker; sides lighter;
skull smaller. From _E. u. montanus_, the subspecies from the
Medicine Bow Range of south-central Wyoming, _E. u. umbrinus_
differs in: Over-all tone of upper parts darker; sides darker;
skull smaller.

_Remarks._--This subspecies occurs only in the foothills of the Uinta Mountains in the southern part of Uinta County. These "foothills" are well-timbered and at an altitude of 7,000 feet and higher.

_Specimens examined._--Total number, 23.

_Uinta Co._: 9 mi. S Robertson, 8,000 ft, 15; 10 mi. S and 1 mi. W
Robertson, 8,700 ft., 5; 11-1/2 mi. S and 2 mi. E Robertson, 9,200
ft., 1; 2 mi. E and 12 mi. S Robertson, Ashley Nat. Forest, 1; 13
mi. S and 2 mi. E Robertson, 9,200 ft., 1.

_Additional records_ (Howell 1929:95): _Uinta Co._: Henry Fork, 5
mi. W Lone Tree; Lone Tree.

Eutamias umbrinus fremonti White

_Eutamias umbrinus fremonti_ White, Univ. Kansas Publ., Mus. Nat.
Hist. 5:575, December 1, 1953.

_Type._--Male, adult, skull, skin, and baculum, No. 41790 (KU);
from 31 mi. N Pinedale, 8,025 ft., Sublette County, Wyoming;
obtained on July 8, 1951, by Rollin H. Baker; original No. 1596.

_Diagnosis._--Size large; over-all tone of upper parts dark; lower
tooth-row longest of this species in Wyoming.

_Description._--_Color pattern_: Crown Cinnamon Buff mixed with
gray; upper facial stripe Sepia; ocular stripe Chaetura-Drab;
submalar stripe Fuscous Black mixed with Sayal Brown; ears black;
anterior margin of ear Mars Yellow; posterior margin of ear grayish
white; hairs inside posterior part of pinna Dresden Brown;
postauricular patch Pale Smoke Gray; median dorsal dark stripe
black; lateral dorsal dark stripes black mixed with Sayal Brown;
outermost dorsal dark stripes Buckhorn Brown mixed with black or
sometimes absent; median pair of dorsal light stripes grayish mixed
with Buckhorn Brown; outer pair of dorsal light stripes creamy
white; sides Buckhorn Brown; rump and thighs Pale Smoke Gray mixed
with Saccardo's Umber; dorsal surface of tail black mixed with
Buckhorn Brown; ventral surface of tail Sayal Brown, with Fuscous
Black around margin and white or Light Buff around outermost edge;
antipalmar and antiplantar surfaces of feet Warm Buff; underparts
creamy white with dark underfur. _Skull_: Large; zygomata strong
and arched; braincase well inflated. _Baculum_: Broad at base;
shaft tapers sharply to tip.

_Comparisons._--From _E. u. montanus_, the subspecies from the
Medicine Bow Range of south-central Wyoming, _E. u. fremonti_
differs in: Over-all tone of upper parts darker; underside of tail
darker; feet darker; sides darker.

For comparisons with _E. u. umbrinus_ see the account of that
subspecies.

_Remarks._--This subspecies normally occurs in the forest as do the other subspecies of _E. umbrinus_ in Wyoming. A single specimen taken at 12 mi. N and 3 mi. W Shoshoni, Fremont County, is the exception which probably indicates that _E. umbrinus_ does occur outside of its normal habitat and that gene-flow exists between the subspecies of this species.

_Specimens examined._--Total number, 53.

_Yellowstone Park_: Unspecified, 2.

_Park Co._: Beartooth Lake, 1 (BS); 16-1/4 mi. N and 17 mi. W Cody,
5,625 ft., 2.

_Teton Co._: 1 mi. E and 1/4 mi. N Togwotee Pass, 9,800 ft., 2;
Amphitheater Lake, Teton Park, 1 (MM); Flat Creek, 4 (MM); head of
Cache Creek, 4 (MM); Jackson, Upper Arizona Creek, 2 (MM); Flat
Creek-Granite Creek divide, 6 (MM); Flat Creek Pass, 1 (MM); Flat
Creek-Gravel Creek divide, 2 (MM).

_Lincoln Co._: La Barge Creek, near source, 9,000 ft., 1 (BS).

_Fremont Co._: Togwotee Pass, 12 (FC); 12 mi. N and 3 mi. W
Shoshoni, 4,650 ft, 1; Mosquito Park R.S., 9,500 ft., 17-1/2 mi. W
and 2-1/2 mi. N Lander, 1; 17 mi. S and 6-1/2 mi. W Lander, 8,450
ft., 3.

_Sublette Co._: 31 mi. N Pinedale, 8,025 ft., 1; W side Barbara
Lake, 10,300 ft., 8 mi. S and 3 mi. W Fremont Peak, 4; 19 mi. W and
2 mi. S Big Piney, 7,700 ft., 5.

_Additional records_ (Howell 1929:95): _Park Co._: Near head of
Clark Fork; Whirlwind Peak near Pahaska, N Fork Shoshone River;
Valley, Shoshone Mountains; Needle Mountain. _Teton Co._: Teton
Mountains, S Moose Creek. _Lincoln Co._: Salt River Mountains.
_Sublette Co._: Gros Ventre Range, 12 mi. NW Kendall; Merna; 8 mi.
W Stanley; Big Sandy. _Fremont Co._: Jackey's Creek, 4 mi. SW
Dubois; Bull Lake, Wind River Mountains; Lake Fork, Wind River
Mountains; Fremont Peak.

Eutamias umbrinus montanus White

_Eutamias umbrinus montanus_ White, Univ. Kansas Publ. Mus. Nat.
Hist. 5:576, December 1, 1953.

_Type._--Male, adult, skull, skin, and baculum; 20105 (KU); from
1/2 mi. E and 3 mi. S Ward, 9,400 ft., Boulder County, Colorado;
obtained on August 1, 1947, by E. L. Cockrum; original No. 721.

_Diagnosis._--Size large; over-all tone of upper parts light; sides
light.

_Description._--_Color pattern_: Crown Raw Sienna mixed with gray;
upper facial stripe and ocular stripe black mixed with Sepia;
submalar stripe Snuff-Brown mixed with black; ear black or Sepia;
anterior margin of ear Ochraceous Tawny; posterior margin of ear
and postauricular patch grayish white; hairs inside posterior part
of pinna Cinnamon Buff; median dorsal dark stripe black with Sayal
Brown along margins; lateral pair of dorsal dark stripes black
mixed with Sayal Brown; outermost pair of dorsal dark stripes Sayal
Brown mixed with black or sometimes lacking; median pair of dorsal
light stripes Pale Smoke Gray mixed with Clay Color; outer pair of
dorsal light stripes creamy white; sides Clay Color; rump and
thighs Neutral Gray; dorsal surface of tail black mixed with
Cinnamon Buff; ventral surface of tail Ochraceous Tawny, with black
along margin and Cinnamon Buff or Ochraceous Tawny along outermost
edge; antipalmar and antiplantar surfaces of feet Cinnamon Buff;
underparts creamy white with dark underfur. _Skull_: Large;
zygomata strong and arched; braincase well inflated. _Baculum_:
Broad at base; shaft tapers sharply to tip.

_Comparisons._--For comparisons with _E. u. umbrinus_ and _E. u.
fremonti_, see the accounts of those subspecies.

_Remarks._--Although in Wyoming this subspecies is known only from the Medicine Bow Range, one would expect to find it occurring in the Snowy Range and the Laramie Range as well, since there seems to be suitable habitat for this subspecies in those mountain ranges.

_Specimens examined._--Total number, 3.

_Albany Co._: 8 mi. ESE Browns Peak, 10,000 ft., 2; 3-1/2 mi. S
Wood's Landing, 1.

REVIEW AND CONCLUSIONS

_Eutamias minimus_ in Wyoming is divisible into two size-groups of subspecies; the smaller size-group (_E. m. minimus_ and _E. m. consobrinus_), which occurs in the western part of the State, is significantly smaller, in measurements of the skull and baculum, than the larger size-group (_E. m. pallidas_, _E. m. confinis_, _E. m. silvaticus_, and _E. m. operarius_) which occurs in the eastern part of the State.

Although all the six subspecies of _E. minimus_ in Wyoming can be differentiated from one another by color pattern, this species cannot be divided, by means of color pattern, into two groups, comparable in geographic range, to the two size-groups that were established above on the basis of variations in the skull and baculum.

Thus, the subspecies of _E. minimus_ are morphologically differentiated at two distinct levels; one level is based on differences in the skull and baculum, while the other is based on differences in color.

Although there is considerable controversy concerning the glacial chronology in the mountains of western North America (Flint 1947:302-303), it is generally agreed that in Wyoming, in Wisconsinan time (the latest glacial age), glaciers covered a large part of the Yellowstone-Teton-Wind River highlands, the Big Horn Mountains, the southern part of the Laramie Range, the Medicine Bow Range, Sierra Madre Range, and the northern foothills of the Uinta Mountains. With this in mind, a possible explanation of the geographic variation in _E. minimus_ of Wyoming, is here attempted.

In Sangamonian time, _E. minimus_-like chipmunks occurred over most of the region which is now Wyoming, and were divided into two size-groups, much as _E. minimus_ is today.

When permanent snow fields were formed in Wisconsinan time, these chipmunks were restricted in their ranges, not, of course, occurring on the glaciers.

When the glaciers melted at the end of Wisconsinan time, new habitats were thus "uncovered." The chipmunks which moved into these ice-free areas, then, became adapted to the new habitats. This then accounts for the subspeciation of _E. m. consobrinus_, _E. m. confinis_, and _E. m. operarius_.

The Black Hills were not covered by glaciers. In late Pleistocene time these hills were probably of low relief. Subsequent differential erosion produced relief sufficient to provide a different habitat. The chipmunks that continued to occupy this area adapted themselves in color to the new habitat and became _E. m. silvaticus_.

LITERATURE CITED

CARY, M.

1917. Life zone investigations in Wyoming. N. Amer. Fauna, 42:1-96,
15 pls., 17 figs.

FLINT, R. F.

1947. Glacial geology and the Pleistocene Epoch. John Wiley and
Sons, New York, pp. xviii + 589, 88 figs., 27 tables, 6 pls.

HALL, E. R.

1926. Changes during growth in the skull of the rodent
Otospermophilus grammurus beecheyi. Univ. California Publ. Zool.,
21:355-404, 43 figs., March 9.

1946. Mammals of Nevada. Univ. California Press, Berkeley,
California, pp. xi + 710, 11 pls., 485 figs., July 1.

HOWELL, A. H.

1929. Revision of the American chipmunks (genera _Tamias_ and
_Eutamias_). N. Amer. Fauna, 52:1-157, 10 pls., 9 maps, November
30.

JOHNSON, D. H.

1943. Systematic review of the chipmunks (genus Eutamias) of
California. Univ. California Publ. Zool., 48:63-148, 1 pl., 12
figs., December 24.

LARRISON, E. J.

1949. Variation in the chipmunks of west-central Washington.
Murrelet, 29:34-43, 1 map, March 1.

SHAW, W. T.

1944. Brood nests and young of two western chipmunks in the Olympic
Mountains of Washington. Jour. Mamm., 25:274-284, 1 pl., 4 figs.,
September 8.

WHITE, J. A.

1953. Taxonomy of the chipmunks, Eutamias quadrivittatus and
Eutamias umbrinus. Univ. Kansas Publ., Mus. Nat. Hist., 5:563-582,
6 figs. in text, December 1.

_Transmitted June 26, 1953._