﻿June, 1896.] SYNOPSIS OF THE WEASELS OF NORTH AMEKICA. 



7 



Similarly iu the far North, where the frozen tundras are inhabited by 

 lemmings as well as voles, two weasels are i>resent: the tiny, narrow- 

 skulled rixosus^ which feeds mainly on mice, and the large, broad-skulled 

 arcticus, which feeds chiefly on lemmings and rabbits. 



It seems clear, therefore, that the different types of weasels have been 

 developed by adaptation to particular kinds of food. 



It is much to be regretted that specimens of the South American 

 weasels are not available for study in connection with the North Amer- 

 ican si^ecies. The only one I have seen is P. affinis Gray, which ranges 

 from Costa Kica to northern South America. While differing si^ecif- 

 ically from frenatns it clearly belongs to the same group. 



Except in winter, weasels are usually so difficult to procure in any- 

 thing like satisfactory series that but few are available from most of 

 the localities rej)resented in collections. As a rule, the number is too 

 small to afford reliable average measurements ,• hence the averages here 

 given are subject to correction. 



The skull drawings in PI. I and those in the text (except figs. 10, 

 11, 15, and IG) were made by Benjamin Mortimer. Those in Pis. II to 

 V, inclusive, were drawn by Dr. James C. McOonnell under the super- 

 vision of the author. About half of the skulls shown in the latter 

 plates were used by Mr. Bangs in his paper already referred to. 



Except where the contrary is distinctly stated, all the measurements 

 in this paper were taken in the flesh by the collector. It is hardly 

 necessary to add that all measurements are in millimeters. 



Genus PUTORIUS Cuvier, 1817. 



Key to suigenera (for American forms only) : 



Size large, about equaling the mink {Lntreola) ; facial bar black; legs and feet 

 abruptly darker tban upper parts subgenus Putorius. 



Size medium or small, never more than balf as large as the mink (Lntreola)', 

 facial bar white or absent; legs and feet concolor witli or x^aler tban upper 

 parts subgenus Ictis. 



Subgenus PUTORIUS Cuvier, 1817. 



Putorius CiwieT: Rc'gne Animal, I, 147-149, 1817. 

 Cynomyonax Couefi: Fur-Bearing Animals, 99, 147-148, 1877. 



PUTORIUS NIGRIPES Aud. & Bacb. Black-footed Ferret. 



(PI. I, figs. 1, la, lb.) 



1851. Putorius mgripes Aud. & Bacli. : Quadrupeds N. Am., Vol. II, pp. 297-299, pi. 

 93, 1851. 



1877. Coues : Fur-Bearing Animals, 149-153, 1877. 



Type locality. — Plains of the Platte Eiver, in Nebraska. 



Geographic range. — Great Plains, from western North Dakota and 

 northern Montana to Texas ; not known west of eastern base of Eocky 

 Mountains. 



Characters. — Size of the mink; ears rather large j color buff}', with a 



