88 Nelson Two New Subspecies of North American Mammals. 



on upper side of tail the rufous heavily overlaid by a zone of black and latter 

 covered by a strong outer wash of whitish ; tail averaging broader and 

 more bushy than in socialis; underparts of body and under side of legs 

 deep, rich rufous ; base of ears behind with a bright patch of white ; a 

 forward extension of nape patch surrounds the eyes ; top of head in front 

 of nape patch darker and more iron gray than back ; cheeks and under 

 side of head whitish. 



Skull. Similar to that of socialis. 



Measurements of type. Total length, 526; tail vertebrae, 273; hind 

 foot, 69. 



Remarks. The present form is based on a series of seven specimens, 

 all from the type locality. So many squirrels have been described from 

 Mexico that it may appear superfluous to name another. However, the 

 present series agree so uniformly in their much paler colors when com 

 pared with the large series of typical socialis in the Survey collection 

 that they evidently represent a well-marked local form. The absence of 

 a rump patch at once distinguishes them from cocos which reaches a point 

 on the coast of Oaxaca not far to the northward. To the south socialis 

 occupies the coast country about Salina Cruz, Oaxaca, while a specimen 

 collected in the mountains half a day's journey on horseback directly in 

 land from Puerto Angel is evidently referable to socialis. This leaves 

 littoralis with a restricted distribution. It is an intergrading form be 

 tween cocos and socialis and nearly as pale as the former, but has lost the 

 rufous rump patch characterizing that subspecies. 



