24 



NORTH AMERICAN FAUNA. 



[No. 40. 



of zygoma correspondingly weak, the shelf and suprajugal arm not 

 especially thickened. Teeth smaller than in the subgenus Cynomys, 

 not so much expanded laterally. 



Type species. — Cynomys gunnisoni (Baird). 



Reraarks. — ^The mountain-inhabiting group of prairie-dogs com- 

 monly known as the ''white- tailed" species form a compact group 

 clearly separated from the typical subgenus. It includes three well- 



BZ120— 129 



Fig. 2. — Distribution of subgenus Leucocrossuromys: 1, Cynomys leucurus; 2, C. parvidens; 3, C. gunnisoni 



gunnisoni; 4, C. g. zuniensis. 



marked species, leucurus, parvidens, and gunnisoni. In habits these 

 are distinctly spermophile-like and in coloration they are peculiar. 

 All have sharply marked areas of color above the eye and on the 

 cheek, and have the tail tipped or bordered with white. 



CYNOMYS LEUCURUS Merriam. 



White-Tailed Prairie-Dog. 



(PL III, fig. 1; PL IV, fig. 1; PL VII, fig. 5.) 



1874. Cynomys columhianus Allen, Proc. Boston Soc. Nat. Hist., XVI, p. 294 (part; 



not Arctomys columhianus Ord, 1815). 

 1890. Cynomys leucurus Merriam, North Amer. Fauna No. 3, p. 59, September 11; 



North Amer. Fauna No. 4, p. 33, October 8. 



