828 MONOGRAPHS OF NORTI1 AMERICAN RODENT I A. 



white, becoming brownish-white on the inside of the limbs; hairs all dark 

 basally. Eyelids white, forming a conspicuous light, eye-ring. Ears inter- 

 nally and posteriorly brownish-yellow; anteriorly dark brown, varying to 

 black. Tail white anil black in alternating longitudinal bands of nearly ecpial 

 width — two black and three white. The hairs individually are white at the 

 tips, with two broad bands of black separated by white; the extreme base is 

 often also black, but usually white. Occasionally presents melanistic phases 

 of coloration. 



Habitat. — Colorado and Western Texas, southward into Mexico, and 

 westward to the Sierra Nevada Mountains. 



General form much as in the true Squirrels (Sciurus). Ears high and 

 broad, as large as in most species of Sciurus. Tail full and bushy, distich- 

 ous; the hairs two to two and a half inches long, giving a breadth to the tail, 

 when the hairs arc outstretched, of four to five inches. Palms and soles 

 (generally) wholly naked. Claws rather short for a Spermophile, yet decid- 

 edly fossorial rather than Sciurine. Pelage coarse but not rigid ; under fur 

 sparse, especially in summer. The hairs, when magnified, are seen to be 

 flattened, with the outer surface grooved. 



Different individuals vary greatly in coloration, the color of the upper 

 surface ranging from nearly pure gray (especially anteriorly) to strong reddish- 

 brown, while that of the lower surface varies from pale yellowish-white to 

 reddish-brown. The gray is generally purest over the shoulders, but is fre- 

 quently developed on the sides of the neck and shoulders, with the inter- 

 vening dorsal space cither darker or more suffused with rufous. There is 

 thus an approach to the distinct gray longitudinal bands seen in vars. beecheyi 

 and douglassi. In several specimens from Soda Springs, Colo, (as in Nos. 

 9565, 9562, and 956 J), and in others from Ogden and Provo, Utah (as in 

 Xos. 11133, 11135, and 11147), the gray forms a continuous mantle, cover- 

 ing the whole anterior half of the dorsal surface, sharply bounded behind 

 by the reddish-brown of the posterior half of the back. In others, the gray 

 blends gradually into the brownish. In some of the Soda Springs and Ogden 

 specimens, the white so predominates over the black as to form a while 

 ground-color minutely grizzled with black In some, the gray mantle is more 

 or less distinctly divided by a mesial space of brownish, thus showing a com- 

 plete resemblance to var. beecheyi. Occasionally, as especially in several 

 specimens collected by Mr. Henshaw in Arizona, the surface of the pelage 



