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.

[Illustration: FIG. 1. Known occurrence and probable geographic
distribution of the subspecies of _Eutamias minimus_ in Wyoming. The
symbols for locality records are as follows: Circles, specimens
reported but not examined; solid circles, precise localities of
specimens examined; solid triangles, localities of specimens
examined, known only to county.

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,
Sweetwa