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MONOGRAPna OP NORTD AMERICAN RODENTIA. 



Spkcific chars. — Size varying greatly with locality. Ucad and boil^ 

 ranging, in ndu ts, from 7 50 to 4.76 inches; tnii-vcrtebraj from 5.00 (or a 

 little more) to 3.50; tail, with hairs, from about 6.50 to 4.25 (occasionally 

 less). Above yellowisli-brown, varying to pale reddish-brown; below white, 

 varying to creamy-white, with sometimes a faint tinge of pale rufous; tail 

 abov(! generally darker than the back, especially at northern localities, where 

 it is sometimes decidedly blackish ; tail below lighter than above, varying 

 with locality from dusky-brown to yellowish-brown, always more strongly 

 colored than th ventral surface of the body. 



Var. HUDBONllTS. 



Northern Flying Squirrel. 



Varietal coars. — Length, exclusive of the tail, 6.00 inches or more; 

 tail, with the hairs about 5.00. Above dull yellowish- or reddish-brown; 

 below white, faintly washed with yellowish; tail above dusky, of>cn decidedly 

 binckish on the edges ond terminal half; also frequently dusky toward the 

 end below. Habitat mostly north of the parallel of 49°, extending further 

 southward along the Rocky Mountains and on the Pacific slope. Grades 

 insensibly into — 



Var. VOLUCELLA. 



Southern Flying Squirrel. 



Varietal chars. — Similar to the preceding, but much smaller. Length, 

 exclusive of the tail, less than 6.00 inches; generally less than 5..'30. Tail 

 Irss dusky, often with no blackish whatever, and the general color of the 

 body above rather more yellowish. Habitat, United States, — exclusive of 

 the Pacific slope north of California, and the Rocky Mountains north of C(d- 

 orado ; and thence southward to Guatemala. 



The American Flying Squirrels present a range of geographical varia- 

 tion in size quite unparalleled in other members of the Sciurida, and only 

 equalled in some species of the Canida, and possibly in Cervus virginianus. 

 On the other hand, the coloration is remarkably constant, almost exception- 

 ally so, no other North American Mammal witli which I am acquainted, 

 which has so wide a geographical range, varying so little in this respect with 

 locality. The species ranges from Arctic America into the tropical portions 

 of the continent. I have specimens before me from points us distant as 



