103 



1870, 12.— Adams, Field and Forest Rambles, 1873, 99, 296 (New 

 Brunswick). — Perkins, Amer. Nat., vii, 1874, 132 (habits in con- 

 finement). 



1828. Sciur'ipte'fus volucella, Geoffroy, Diet. Class. Hist. Nat., xiv, 1828, 

 132.— Jordon, Man. Vert., 1878. 



1874. Sciuroptents volucella, var. volucella, Allen, Proc. Bost. Soc. Nat. Hist , 

 xvi, 1874, 189; Bull. Essex Inst., vi, 1874, 66; Mon. N. A. Ro- 

 dentia, 1877, 665. 



Specific Characters. — Size varying with locality; head and body ranging 

 in adults from 7.50 to 4.75 inches; ta'il vertebrae from 5.00 to 3.50; tail, 

 with hairs, from 6.50 to 4,25, and even less. 



Yellowish-brown to pale reddish-brown above, white to creamy white 

 below, with sometimes pale rufous ; tail above usually darker than back — 

 decidedly blackish in some northern forms. 



History and Varieties of Species. — The Flying Squirrels were separated 

 from ordinary Squirrels in 1800, by G. Cuvier, under the generic name 

 Pteromys. 



In 1825, F. Cuvier separated the small Flying Squirrels of Europe and 

 North America from the others, under the name Seiuropterus, calling 

 attention to the cranial and dental differences, as well as to the evident 

 difference in size and shape of tail. 



The wide geographical variation in size has led to the recognition of 

 several species in North America. Prof. Baird, in 1858, with few speci- 

 mens at hand, hesitatingly admitted four species — volucella, hvdsonivs, 

 alpinus, and oregonensis. 



Mr. J. A. Allen, in Monographs of North American Rodentia, recog- 

 nizes one species with two varieties. The synonymy of var. volucella is 

 given above. 



Seiuropterus volucella, var. hudsonius, Allen, Proc. Bost. Soc. Nat. Hist., 

 xvi, 1874, 289, is the northern form known as Sciurus hudsonius, Gmelin, 

 1788; Pteromys hudsonius, Fischer, 1825; Sciurus sabrinus, Shaw, 1801; 

 Pteromys sabrinus, Rich., 1828; Pteromys alpinus, Wagner, 1843; Greater 

 Flying Squirrel of Forster, 1772, etc. 



The northern form is large, with the tail dusky to dark, and the gen- 

 eral color of the body above less yellowish ; it grades insensibly into the 

 Southern Flying Squirrel. "There is," says Mr. Allen, " no break in the 

 sequence from north southward, either in size, color, or other characters, 

 by which the group can be subdivided either specifically or varietally." 

 The recognition of a northern and southern sub-species is almost entirely 

 arbitrary. 



The alteration in average size with the latitude already referred to in 

 the case of the Virsfinia Deer, nearly all species of eixtensive north 



