New Ground Squirrels. 131 



with the much darker tints of the neck and back which are com- 

 pletely covered with the new coat. The two are separated by a 

 sharp line of demarkation that crosses the occiput between the 

 ears. 



Heretofore no species of the Ammospermophilus group has 

 been recorded from the San Joaquin Valley, or in fact from any 

 point west of the great divide. It is remarkable that a diurnal 

 mammal as conspicuous as the present species, and one inhab- 

 iting a region traversed by a railroad over which numerous 

 mammal collectors have passed again and again, should have 

 remained undescribed to the present day. 



Speimophilus perotensis sp. nov. 



PEROTE SPERMOPHILE. 



Type from PEROTE, VERA CRUZ, MEXICO. No, 54274 9 ad. United 

 States National Museum (Department of Agriculture collection). Col- 

 lected by E. W. Nelson June 8, 1893 (original number, 4976). 



Measurements (taken in. flesh). Type specimen: Total length, 253; tail 

 vertebrae, 68 ; hind foot, 39. Average of 14 specimens from type locality : 

 total length, 249; tail vertebrae, 69; hind foot, 38.5. 



General Characters. This spermophile does not require com- 

 parison with any known species. In size and external appear- 

 ance it resembles S. elegans of Wyoming, but its cranial characters 

 show it to belong to another subgenus (Xerospernwphilus). Ears 

 a mere rim ; tail rather short. 



Color. Upper parts grizzled yellowish brown, vermiculated 

 posteriorly by irregularly interrupted lines of black (which in 

 immature specimens, and probably also in new pelage in adults, 

 form the posterior borders of indistinct buffy spots) ; eyelids 

 white ; under parts and feet buffy. Tail above, grizzled yel- 

 lowish brown and black, the black predominating on the distal 

 half; below, ochraceous buff, with a distinct subapical band of 

 black encircling the distal half or two-thirds. 



Cranial Characters. In cranial characters Spermophilus pero- 

 tensis clearly belongs to the subgenus Xerospermophilus, and to 

 that part of the subgenus from which the ancestors of S. mexi- 

 canas branched off. The adult skull is larger and heavier than 

 that of any other known member of the spilosoma group, and re- 

 sembles S. spilosoma major more closely than any other species. 

 The parietals are much more highly arched above the supra- 

 occipital, the highest point being between the postorbital pro- 



