1916.] 



CYNOMYS LEUCUKUS. 



25 



1898. Cynomys levjisii Allen, Bull. Amer. Mus. Nat. Hist., X, p. 456, November 10 



(not Arctomys lewisii Audubon and Bachman, 1854). 

 1904. Cynomys lewisi Trouessart, Cat. Mamm., suppl., p. 342. 



Type locality. — Fort Bridger, Sweetwater County, Wyoming. 



Geographic distribution. — Irregular areas in the mountainous parts 

 of Montana, Wyoming, Utah, and Colorado. South from the Bighorn 

 Basin, in southern Montana, across central and southwestern Wy- 

 oming into western Colorado and northeastern Utah ; east to the Lara- 

 mie Mountains, Wyoming, and into North Park, Colorado; south into 

 the lower Gunnison Valley; west a few miles across the Bear River 

 Divide into extreme northern Utah and, farther south, into the Green 

 River valley. Chiefly Transition Zone. 



Cliaracters. — Size, largest of the subgenus, only slightly smaller than 

 in Cynomys ludovicianus, but tail much shorter; general coloration 

 less reddish, more grayish buff than in C. parvidens; differs from C. 

 gunnisoni in having terminal half of tail entirely white; supraorbital 

 spot and cheek dark brown. 



Color. — Adult in fresh summer pelage: General color of upper parts 

 yellowish buff, streaked with blackish. Nose yellowish buff, un- 

 marked; spot above eye and large area on cheek dark blackish brown; 

 ears pale cinnamon. Top of head to center of tail uniformly mixed 

 pale cinnamon-buff or yellowish buff and blackish; the individual 

 hairs black at bases, then light gray, then pale cinnamon, with sub- 

 terminal band of buff and, in unworn condition, tip of blackish. 

 Limbs, feet, and underparts clear buffy; nails blackish, tipped with 

 light horn. Tail white, the hairs of proximal half above with bands 

 of blackish, below pale cinnamon; distal half clear white. Adult in 

 fresh winter pelage: Decidedly darker than in summer; more blackish 

 above, especially posteriorly; the buff tints richer in tone and the 

 dark areas on head considerably spread out, less sharply defined. 

 There is a heavy underfur of grayish white, but the bases of all the 

 hairs are clear black; sides of nose, chin, and throat white; nape and 

 flanks lighter, more grayish, than back and rump. Juvenile pelage: 

 Above grayish brown; below paler grayish; supraorbital spot of 

 brownish black sharply marked. Postjuvenile pelage: Specimens in 

 first fresh autumnal coat darker than adults, more reddish, and hairs 

 of upperparts more heavily tipped with blackish. 



Adults in the faded, left-over winter coat are often very yellowish 

 above, with little or no black streaking from the hair tips. Many 

 specimens in various stages of molt and renewal present strange com- 

 binations of color. Examples deeply stained by color from the soil 

 are frequently noted. 



Molt. — The two annual molts are greatly affected by altitude, with 

 a consequent variation of a month or more in near-by localities. In 

 Wyoming the molt is approximately as foUows: Specimens taken 



