WINGS OF BATS 
which bats scramble about rocks and trees, recalls the similar 
organ in that primitive, lizardlike bird, the archeopteryx. The 
body is small, with a capacious chest to contain the very large 
lungs and heart, and to support the wing muscles; and the breast- 
bone is keeled. The skull is almost as large as the chest, with 
wide nostrils and ears but minute eyes (except in the fox bats), 
and the mouth has thirty-eight teeth of the usual four kinds, but 
LITTLE BROWN BAT OF THE EASTERN UNITED STATES. 
all with very sharp cutting edges and the canines frequently 
long and needlelike. The pelvis, on the contrary, is weak, and 
the hind limbs are small, while the knee bends backward because 
of the outward twist of the limb. This makes the foot almost 
useless for walking, but fits it, with its peculiarly strengthened 
ankle, to be extended straight backward, and serve as a means 
of hanging the body, head downwards — the bat’s ordinary 
attitude in rest or sleep. 
The wing-membrane is the most striking feature of bats, and their chief 
reliance not only for moving about, but for information, since its surface 
is so exquisitely sensitive that apparently the animal becomes Wing 
aware of the nearness of a solid object approached in utter dark- Membrane. 
ness, when the eyes — which at best are minute and buried in fur — could 
not perceive it. Indeed, in the often-quoted experiments by Spallanzani,* it 
was shown that blinded bats could fly swiftly about in a room full of dangling 
strings and other obstacles without touching one, alight easily where they 
pleased, and apparently travel without any inconvenience. Schobl and 
others have verified these disclosures, and have explained them by micro- 
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