796 MONOGRAPHS OF NOUTLI AMERICAN K0DE5TIA. 



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. 



Tovmsend's Ch ipm unk. 



Varietal chars. — Size large, equalling that of Siberian specimens of 

 var. boreal'is. Length of head and body 5.30 ; of tail to end of vertebra?. 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. 



Habitat. — Pacific coast, from Northern California to British Columbia; 

 at the southward and eastward passing into var. quadriuittatus 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 other 

 forms ; the light stripes rather whiter (sometimes nearly pure white) than 

 usual in the others. 



A desert phase of var. townsendi, holding the same relation to that form 



