THE MAMMALS OF NEW JERSEY. 93 
The “wings” consist of immensely elongated fingers, between 
which is a delicate Indiarubber-like membrane, which extends 
down along the sides of the body to the hind feet, and also out 
to the tip of the tail. The toes on the hind feet are not elongated, 
and they, as well as the short-clawed thumb of the hand, are 
used in grasping limbs, or other support, when they come to rest, 
or wish to hang themselves up. 
Bats fly about at dusk and just before dawn and, to some 
extent, throughout the night, and feed on insects of various 
sorts which they catch on the wing. They may often be seen 
about electric arc-lights, where such vast hosts of insects are 
assembled every night during the summer, and where they must 
be able to make an ample meal. During the day they hang in 
trees concealed among the leaves, or congregate in dark garrets, 
under the eaves of buildings, or in caves, or similar places of 
refuge. Their teeth are somewhat like those of the shrews— 
small and sharp, and their eyes are quite small. They utter an 
extremely shrill, grating squeak when caught and irritated. Bats 
are strictly beneficial to man, and in spite of the numerous 
stories and superstitions connected with them, they are abso- 
lutely harmless, and should be welcomed about our houses, 
rather than driven away. Their repellant appearance and un- 
pleasant musky odor will, however, always make them unde- 
sirable visitors to the majority of mankind, in spite of their 
good qualities. 
All of our New Jersey bats belong to a single family, the 
V espertiliomde. 
Family VESPERTILIONIDA. 
OrDINARY BATs. 
Our Bats belong to five genera, distinguished as follows: 
a. Membrane between the hind legs (interfemoral membrane), completely 
furred above, uniform with back. LASIURUS 
aa. Interfemoral membrane naked or only slightly hairy near the base. 
b. Fur black with white lips. LASIONYCTERIS 
