352 VERTEBRATE ANIMALS OF THE UNITED STATES 



M.f. warreni How. Size large; colors deep red with buff: western 

 Colorado. 



M.f. ohscura How. Size large; color dark brown, mixed with white: 

 northern New Mexico and southern Colorado. 



M. caligata (Eschscholtz) . Whistler. Color of fore part of back 

 white, hinder and sides of body part cinnamon, mixed with black; under 

 parts white; feet and top of head black; length 755 mm.; tail 250 mm.; 

 hind foot no mm.: Alaska to Washington and Montana. 



Subspecies of M. caligata 



M. c. nivaria How. High mountains of northwestern Montana and 

 northern Idaho. 



M. c. cascadensis How. Head and feet browner and under parts 

 darker: Cascade Range, Washington; southward to Mount Rainier. 



M. c. olympus (Merr.). Color brownish drab; feet brown: upper 

 slopes of Olympic Mountains. 



9. Sciuropterus F. Cuvier. Flying squirrels. Small rodents with 

 a broad furry membrane stretching between the front and hind legs and 

 extending out from the sides; tail flattened; ears large; dentition i/i, 

 0/0, 2/1, 2,lz'- about 15 species; in the northern hemisphere; 3 species 

 in the United States, nocturnal animals which make their nests in 

 holes in trees; from 2 to 6 young form a litter, of which there probably 

 are several a year. 



Key to the Species of Sciuropterus 



ai In the eastern and central States. 



bi Belly pure white 5. volens. 



b2 Belly dirty white 5. sahrinus. 



a2 In the Rocky Mountain and Pacific slope region S. alpinus. 



S. volans (L.). Color drab above ringed with reddish; beneath pure 

 white; length 230 mm.; tail 100 mm.; hind foot 37 mm.; fur soft and 

 dense: eastern and central States from southern Maine to Florida; 

 westward to the plains. 



Subspecies of S. volans 



S. V. querceti Bangs. Color more uniform russet: Gulf States from 

 Georgia to Texas. 



S. sabrinus (Shaw). Color drab above and dirty white beneath; 

 length 280 mm.; tail 125 mm.; hind foot 42 mm.: northeastern and 

 central States and Canada; southward into Massachusetts and northern 

 New York; northwestward to x\laska. 



