103 
1870, 12.—Adams, Field and Forest Rambles, 1873, 99, 296 (New 
Brunswick).—Perkins, Amer. Nat., vii, 1874, 182 (habits in con- 
finement). 
1828. Sciur:pterus volucella, Geoffroy, Dict. Class. Hist. Nat., xiv, 1828, 
132.—Jordon, Man. Vert., 1878. 
1874. Sciwropterus volucella, var. volucella, Allen, Proc. Bost. Soc. Nat. Hist., 
xvi, 1874, 189; Bull. Essex Inst., vi, 1874, 66; Mon. N. A. Ro- 
dentia, 1877, 655. 
Specific Characters.—Size varying with locality; head and body ranging 
in adults from 7.50 to 4.75 inches; tail vertebree 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 Hurope and 
North America from the others, under the name Sctwropterus, 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 specti- 
mens at hand, hesitatingly admitted four species—volucella, hudsonius, 
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. 
Sciuropterus 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; Sciwrus 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 Flving 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 Virginia Deer, nearly all species of extensive north 
