AMERICAN FLYING SQUIRREL. 103 
These squirrels inhabit hollow trees ; where they 
sleep during the day, and from whence they only 
make their appearance in the night ; at which lat- 
ter time they are very lively and active. They as- 
sociate in flocks ; several living in the same tree* 
which they never willingly quit to run upon the 
ground, but almost constantly reside among the 
branches. By means of their lateral membranes, 
they are able to make astonishing leaps, with the 
greatest ease, from tree to tree. In these efforts 
they extend their hind legs, and stretch out the in- 
tervening skin, by which they present a greater 
surface to the air, and become more buoyant. 
They are, however, still under the necessity of tak- 
ing-advantage of the lower branches of the trees 
to^which they leap, for their weight prevents them 
from keeping in a straight line. Sensible of this, 
they always take care to mount so high as to en- 
sure them from falling to the ground. This ex- 
tended skin acts upon the air somewhat in the 
manner of a paper kite, and not by repeated 
strokes like the wings of a bird. The animal 
being naturally heavier than the air, must of 
course descend ; the distance, therefore, to which 
it can jump, depends on the height of the tree on 
which it stands. When it is at rest, the skin is 
wrinkled up against its sides. 
These animals are generally seen in flocks of ten 
or twelve ; and to persons unaccustomed to them, 
they appear at a distance, in their leaps, like leaves 
blown from the trees by the wind. “ When I 
first saw them,” says Catesby, I took them for 
dead leaves blown one way by the wind ; blit was 
not long so deceived, when! perceived many of 
them follow one another in the same direction. 
They will fly fourscore yards from one tree to 
another.” 
The females produce three or four young at a 
