62 MAMMALIA. 



gans of flight. The first of these, however, requires several subdi- 

 visions. 



VESPERTILIO, Lin. 



The arms, fore-arms and fingers of the Bats are excessively lengthened, 

 forming-, with the membrane that occupies their intervals, true wings, pos- 

 sessing even a greater extent of surface than those of Birds they conse- 

 quently fly very high, and with great rapidity. The thickness of their 

 pectoral muscles is proportioned to the motions they have to execute, and 

 there is a ridge in the middle of the sternum like that of Birds, to which 

 they are attached. The thumb is short and armed with a claw, by which 

 they are enabled to creep and to suspend themselves. Their hind feet are 

 weak and are divided into five toes, almost always of equal length, armed 

 with trenchant and pointed nails. Their eyes are excessively small, but 

 their ears are frequently very large, and together with the wings form a 

 vast membranous surface, which is almost naked, and so extremely sensi- 

 ble that it is probable they guide themselves through all the sinuosities of 

 their labyrinths, even after their eyes have been plucked out, solely by the 

 diversity of the impressions of the air. They are nocturnal, and in our 

 climate pass the winter in a state of stupor. During the day they suspend 

 themselves in obscure places. They generally produce two young ones 

 at a birth, which cling to their mammx, and whose size is considerable in 

 proportion to that of the mother. This genus is very numerous, and offers 

 many subdivisions. We must begin by separating from it the 



PTEROPTTS, Bris. 



Trenchant incisors in each jaw, and grinders with flat crowns; the food, 

 consequently, consists chiefly of fruit, of which it destroys considerable 

 quantities; it also successfully pursues birds and small quadrupeds. It is 

 the largest Bat known, and the flesh is eaten. It inhabits the East Indies. 



They have never been found out of the south of Asia or the Indian Ar- 

 chipelago. 



a. Without tails, and four incisors in each jaw. 



P. edulis, Geoff. (The Black Roussette.) Blackish brown, deepest be- 

 neath, wings nearly four feet from tip to tip. From the Moluccas and the 

 straits of Sunda, where they are found in great numbers during the day 

 suspended to the trees. 



b. With a small tail and four incisors in each jaw. 



M. Geoffrey was the first who described the species of this subdivision. 

 One of them grey and woolly, Pter. aegypticus, is found in the caves of 

 Egypt. 



The Pteropi being taken away, we have the true BATS left, which are 

 all insectivorous, and have three grinders on each side in each jaw, bristled 



