species the leg is armed with long spurs homologous with the 
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during flight. The first finger may be reduced oe a aineiele $ 
phalanx and the other digits may also be somewhat reduced — 
but they never coalesce as in birds. The thumb is commonly ~ 
furnished with a nail which frequently serves as a support 
during the day-time or period of winter repose. The other 
fingers are greatly elongated and are very strong and elastic, 
Usually if a bat is brought down by a blow it willbe found that | 
the humerus, or short bone of the arm, is broken while thie: Da oh 
more slender phalanges are intact. 
The volatory apparatus, however, consists, besides the wing *3 
of various other membranes, or rather continuations, of the ct 
web above mentioned. The humeral portion is a triangular he 
gib-like membrane passing from the wrist to the sides of the 
neck or shoulder, and is, in some species, pocket-like. There — ee 
or 
wk 
ied 
i 
if 
web corresponds to that expansion of the skin which Peas ‘a 
a parachute by which flying squirrels ‘‘fly.” Another portion, = 
the interfemoral membrane, connects the feet with each other. - 
The tail is ordinarily included in this membrane, butits apex — 
may extend beyond, or it may be entirely wanting. In some 
cartilage upon the wrist of the flying squirrel which serve as 
supports to the web. 
The form is various, but is uniformly plump with a short ah 
neck and thick body. i) 
When not in motion the ensemble is bizarre and formless. 
(See Fig. 1, heads of various bats.) The smaller bats resemble | I; 
mice in their pelage and general appearance and are retaliative 4 , 
and fierce when caught. ie 
The head is rendered remarkable by enormously expanded — 
ears, often provided with a large simple or lobed tragus which — 
serves as a sort of valve for closing the ear. In many species” 
the nose is also ornamented with extraordinary folds of skin, 
which seem 1o be the seat of the delicate tactile sense for which _ 
bats are distinguished. The eyes of bats are very small,andseem _ 
adapted to the peculiar nocturnal habits of the animal, but are 
supplemented by the senses of touch and hearing. Inaroom, 
across which wires have been stretched in all directions, a bat — 
will fly freely without dashing against them even when the ~ 
eyes are destroyed or blindfolded. 
The volar membrane is itself very sensitive, being richly 
supplied with nerves as well as bloodvessels. In the eye of | 
nocturnal animals, generally the spindle-shaped bodies in the 4 
