I 93-] Allen, Mammals from New Mexico and Durango. 597 



The two extremes are both old males and measure respectively: 

 Total length, smallest, 451, largest, 540; head and body, 241 and 298; 

 tail vertebrae, 210 and 248; hind foot, 57 in both; ear, 25 and 28. The 

 females average slightly smaller than the males, and present a much 

 less range of variation, none being nearly as small as the smallest male, 

 nor are any as large as the largest males. 



This subspecies most resembles C. grammurus, but differs 

 from it in being larger, in having the crown and nape (usually) 

 black, the shoulders and sides less white, and the ventral sur- 

 face deep buff. It is characterized also by a larger and much 

 heavier skull, with heavier dentition. It is very distinct from 

 C. variegatus of the Valley of Mexico and contiguous areas, 

 which is a much darker animal throughout, and also larger, 

 and in which the dark crown patch is only incipiently de- 

 veloped. It is more than probable, however, that the whole 

 series of line-tailed spermophiles, from the Valley of Mexico 

 northward to Colorado, will prove to be intergrading forms of 

 the long-known grammurus group, as suggested by Mr. Nelson 

 in his note on Erxleben's Sciurus variegatus. 1 



At first it seemed probable that this series of Durango speci- 

 mens must represent Spermophilus macrourus of Bennett (P. 

 Z. S., 1833, p. 41), although Mr. Nelson had synonymized it 

 with Sciurus variegatus Erxleben, later (1830) renamed Sper- 

 mophilus buccatus by Lichtenstein. Through the kindness of 

 Dr. A. K. Fisher, Acting Chief of the U. S. Biological Survey, 

 I have before me four typical examples of Citellus variegatus, 

 collected by Mr. E. W. Nelson in the Valley of Mexico and 

 the adjoining State of Puebla, and a series of exactly similar 

 specimens from Zapotlan, southern Jalisco, collected for this 

 Museum by Dr. Buller. Bennett's description applies much 

 better to this form than to the Durango specimens, and it 

 seems therefore preferable to consider Bennett's macrourus as 

 a synonym of variegatus, as Nelson has done, or else to regard 

 it as unidentifiable. The final settlement of the case must 

 rest on an appeal to the type, which may still exist in the 

 British Museum. 



1 Nelson, E. W. What is Sciurus variegatus Erxleben? Science, N. S., VIII, No. 

 208, pp. 897, 898, Dec. 23, 1898. 



