G80 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



or grayish-white, rarely with faint annulations of black. In summer speci- 

 mens, there is generally a more or less distinct black lateral line; in many, 

 it is, however, nearly obsolete, and is sometimes wholly absent, as it appears 

 to be generally in winter specimens. The tail is black, edged with gray; the 

 terminal third, however, often wholly black. The tail-hairs are at the base 

 generally gray, but sometimes more or less fulvous, and even rufous. 



In this variety, the middle of the back is not generally redder than the 

 rest of the dorsal surface; the reddish dorsal baud, so characteristic of the 

 other varieties, being absent. The general color above is hence nearly uniform 

 gray, more or less strongly tinged with yellowish- or reddish-brown. The 

 tail generally has also no fulvous or rufous at the base of the hairs which are 

 gray at base and tipped with whitish. These are the two principal features 

 of distinction between the present variety and vars. richardaoni and douglassi. 

 Specimens, however, from various localities, have more or less red or fulvous 

 at the base of the tail-hairs, and, in some specimens, the tail is washed with 

 pale yellowish instead of white. In the extreme phase of this species, the 

 tail is centrally above pure light gray, sometimes tinged slightly with yel- 

 lowish or rufous. No. 11679, from Fort Garland, Colo, has the tail 

 centrally reddish-yellow to the end of the vertebra?, and edged with pale 

 yellowish-white. The general color varies from pale fulvous, varied minutely 

 with black, to strong yellowish-rufous. The sides are usually paler than the 

 back, but there is never a well defined dorsal band. The feet and outer side 

 of the limbs are frequently golden. 



Var. fremonti ranges from the eastern base of the middle portion of the 

 Rocky Mountains to the Pacific (some of the specimens from Fort Crook, 

 Cal., being undistinguishable from Colorado ones) and from New Mexico 

 to Southern Montana and Idaho. Specimens from Bear Creek, Oregon, 

 and from the Uintah Mountains are typically of this variety; Fort Bridger 

 specimens are nearly so. Farther northward, it. passes into var. richardsoni, 

 and in California merges imperceptibly into var. douglasci. Several of the 

 California specimens (Nos 3848 and 3846, from Fort Crook) have the under 

 parts pure white, the tail centrally gray and washed with white, and the 

 upper surface uniformly colored; hence closely resembling var. fremonti. 

 Others (Nos. 3316 and 4664), from the same locality, arc strongly fulvous 

 beneath, like some (No. 1160, for example) of the specimens from the Upper 

 Des Chutes Valley, and even more strongly so than Nos. 1956 and 1420, 



