SCTURIDA—SCIUROPTERUS VOLUCELLA. 659 
scarcely darker or more fulvous than the ventral surface of the body; again, 
and more frequently, the lower surface of the tail is nearly as dark as the 
dorsal surface of the body, from which it differs only slightly in tint. As 
already noticed, the edges and terminal portion of the lower surface of the 
tail are occasionally strongly dusky. Commonly, the eye is encircled by a 
narrow dusky ring, and there is a dusky spot in front of the eye; but some- 
times these markings (in light-colored specimens) are wholly obsolete 
Occasionally, there is a whitish spot at the posterior base of the ear, sometimes 
conspicuously noticeable, while in the majority of instances no such marking 
is clearly distinguishable. Also, in southern specimens, the pelage of the 
lower surface is wholly white to the base; in others, the basal portion is 
dusky, as is generally the case in northern specimens, in some of which only 
merely the surface is whitish. 
Doubtless, the small amount of variation in color with locality, apparent 
in this group, as in the Hares (see anted, p. 268), is in part owing to mode 
of life, these animals being not only nocturnal, but habitually passing the 
day-light concealed in hollow trees. They are hence apparently less exposed 
to the influences most active in modifying coloration. 
As already intimated, the habitat of this species embraces nearly the 
whole of the North American continent. Its range to the northward extends 
apparently to the forest limit, there being specimens in the collection from 
Labrador, the vicinity of Great Slave Lake, Fort Liard, and Alaska. There 
are also specimens from Georgia, Mississippi, and Louisiana. It is well known 
‘as an inhabitant of Mexico, and Mr. Salvin collected it at Duenas, Guatemala. 
Mr. Tomes refers to his specimens as having the fur a little coarser, and the 
color everywhere more rufous, than in specimens from the United States.* 
Examples have been received from so many parts of the interior, as well as 
from the Pacific coast, that it may be considered as presumably dispersed 
throughout the wooded portions of the continent. Even where it is common, 
it is a species not often observed, owing to its nocturnal habits. Audubon 
and Bachman, in their very interesting biography of this species, speak of it 
as being to some extent gregarious. 
The great amount of geographical variation in size presented by this 
species has led to the recognition of several supposed species. As early as 
“Proc. Zoél, Soc. Lond. 1861, p. 281. 
