2 74 VERTEBRATE ANIMALS OF THE UNITED STATES 



Subspecies of M. pennanti 



M. p. pennanti (Erx.). Forests of northern America. 



M. p. pacifica (Rhoads). Size large; length 1,090 mm. : Pacilic slope 

 from California to Alaska. 



2. Mustela L. {Putorius Cuvier). Weasels and minks. Body 

 elongate and very slender, the two sexes differing very much in size; 

 feet digitigrade; pads of feet separate; dentition 3/3, i/i, 3/3, 1/2 

 (Fig. 158); color in summer sharply bicolor (except the mink, which 

 is unicolor), brown above and white beneath, becoming, in many 

 species, pure white in the winter: cosmopolitan; 22 species in North 

 America, 15 in the United States. Weasels are forest animals which 

 feed on all kinds of small mammals and birds, and are noted for their 

 ferocity and blood-thirstiness, which often leads them to kill much more 

 than they can eat. They are essentially terrestrial animals, but can 

 run about in trees with the agility of squirrels. Their dens are in 

 hollow logs or in burrows in sheltered places, and they bear usually 

 about 6 young a year, although sometimes as many as 12. 



Key to the United States Species of Mustela 



ai Length under 500 mm.; toes without webs; weasels, 

 bi In the eastern States. 



Ci From New England to North Carolina M. noveboracensis. 



c-2 New England, New York and northwards M. cicognanii. 



C3 In Maine M. occisor. 



C4 In Florida M. peninsulce. 



Cs In western Pennsylvania M. aUegheniensis. 



hi In the central plains and the mountains. 



Ci From Minnesota northwards M. rixosa. 



C2 From Kansas northwards M. longicauda. 



C3 In the Sierras and Rockies M. arizonensis. 



C4 In the Black Hills M. alleni. 



ba On the Pacific slope. 



Ci In California and Oregon M. xanthogenys. 



C2 In Oregon and Washington M . satiirata. 



C3 In Washington M. washingloni. 



C4 In the Puget Sound region M. streatori. 



a-2 Length greater than 500 mm. 



bi Color brown; minks M. vison. 



hi Color yellowish; ferrets M. nigripes. 



M. noveboracensis (Emmons). Long-tailed weasel; common weasel 

 (Fig. 157). Color in summer brown above and white or yellowish 

 beneath; posterior third or half of tail black; color in winter white 

 towards the north and drab towards the south, except the end of the tail, 



