New Ground Squirrels. 135 



lete. Tail rich -orange-rufous both above and below and only 

 narrowly margined with black. Hind foot shorter than in any 

 other member of the speciosus group. 



Color. Winter pelage : Top of head and rump ash gray; back 

 of neck and inner pair of dorsal light stripes pale vinaceous drab, 

 fading into gray posteriorly ; dorsal stripes short, not continuing 

 over rump ; outer pair of light stripes dull whitish ; all five dark 

 dorsal stripes dull fulvous ; sides gray, washed with buffy ochra- 

 ceous. Face stripes indistinct; those below the eye obsolete. 

 Tail: upper surface rich orange rufous (from the broad sub-basal 

 zone of this color), which is only heightened by the narrow sub- 

 apical zone of black and the yellowish tips of the hairs ; under 

 surface deep orange rufous, with a narrow submarginal band of 

 black, bordered with yellowish. 



Summer Pelage : Similar to winter pelage, except that the sides 

 and dark dorsal stripes are suffused with ferruginous, and the 

 median part of the central stripe is blackish posteriorly. 



Cranial Characters. Skulls of T. panamintinus resemble those 

 of T. quadrivittatas from the type locality in Colorado so closely 

 that the two are hardly distinguishable, though the skull of the 

 Panamint animal is slightly smaller and more depressed in the 

 fronto-nasal region, and has larger audital bullse. Contrasted 

 with T. speciosus, the brain case is flatter and the audital bullse 

 conspicuously larger. 



General Remarks. In winter pelage panamintinus differs from 

 speciosus, the only form with which it requires comparison, in 

 having all of the stripes less distinct, particularly those of the 

 face and ears ; the dorsal stripes shorter, not running back over 

 the rump, which is clear gray ; the outer pair of white stripes 

 narrower, shorter, and less pure white; the dark dorsal stripes 

 pale fulvous instead of dark umber ; the shoulders and back of 

 the neck suffused with buffy-ochraceous instead of being gray, 

 and the rufous of the distal half of the tail not obscured by 

 black. 



In summer pelage it resembles speciosus much more closely, 

 but may be distinguished by less vivid tints, paler facial stripes, 

 narrower outer dorsal white stripe, obsolescent ear stripes, pale 

 gray rump, and by the small amount of black on the tail. In 

 all pelages the black on the tail is very much restricted, permit- 

 ting the rufous to show through on the upper surface for its 

 entire length, thus imparting to it a peculiar ruddy glow not 

 seen in any other species. 



