796 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
stone and adjoining region, and of the arid districts of Wyoming, Southern 
Idaho, Utah, Nevada, Arizona, and New Mexico. Reaches an extreme phase 
of specialization in the Yellowstone region in respect to both pallor and 
smallness of size. 
Var. TOWNSENDI. 
Townsend's Chipmunk. 
VARIETAL CHARS.—Size large, equalling that of Siberian specimens of 
var. borealis. Length of head and body 5.30; of tail to end of vertebrae 4.25 ; 
to end of hairs about 5.00. General color above nearly uniform dull rusty- 
brown, with usually five (sometimes only three) distinct longitudinal stripes 
of black. Intervals between the dark stripes generally, but not always, some- 
what lighter than the general color; sometimes much lighter (yellowish-gray); 
occasionally the outer light stripes are clear grayish-white. Markings on the 
head the same in number, size, and position as in the preceding, but the light 
ones are more rufous and the dark ones blacker. The tail-hairs are deep 
rust-red at base, with a subterminal bar of black and clear grayish-white tips. 
Hasirat.—Pacific coast, from Northern California to British Columbia ; 
at the southward and eastward passing into var. guadrivittatus and at the 
northward into var. borealis. Most specialized near the mouth of the Colum- 
bia River, where it attains the largest size and darkest tints. 
Var. DORSALIS. 
Gila Chipmunk. 
VARIETAL CHARS.—Of medium size for the species, being intermediate in 
this respect between the extreme phases of vars. townsendi and quadrivittatus. 
General color above ashen-gray, varied slightly with yellowish-brown ; sides 
pale dull yellowish. Dorsal surface with a single blackish stripe along the 
middle of the back, extending from the occiput to the base of the tail. The 
other dorsal stripes are nearly or quite obsolete, though generally traceable ; 
the outer white stripes generally more distinct than the others. Hairs of the 
tail pale rust (sometimes bright rusty-red) at the base, with a subterminal 
border of black edged with whitish. Markings of the head as in the otier 
forms; the light stripes rather whiter (sometimes nearly pure white) than 
usual in the others. 
A desert phase of var. cownsendi, holding the same relation to that form 
