TRIBE OF BATS. 43 



in motion by the limbs of the animal, performs the office of a para- 

 chute, by the help of \vhich he is enabled to sustain himself in the 

 air, when he springs from an elevated point (Plate 2,/fy. l,and 7.) 



6. All these animals are not equally well organized for flight, 

 and on this account, they may be divided into tribes, as follows : 



(Tribes., 



/" Having wings, (formed by a mem-^ 

 I brane which is sustained by excessively ^ Bat. 



Family | long fingers.) J 



of { Having parachutes, (formed by a fold ~\ 



CHEIROPTERA, I of skin on the sides which extends between I ~ 7 . , 



the limbs, but a very little amongst the ( ' ******* 

 [jingers, (toes) which are short, J 



Tribe of Bats. 



7. These singular animals, (Plate 2, fig. 1, and 2.) seem at 

 first sight, to partake as much of the bird as of the mammiferous 

 animal, for, like the first, they are provided with strong wings, 

 and are organised for flying in the air, rather than walking on 

 the ground ; but if we examine the structure of their body with 

 more attention, we perceive that, in reality, it differs only in a 

 very slight degree from that of the ordinary mammalia, and these 

 anomalies chiefly depend upon the extreme elongation of all parts 

 of their anterior extremities. The wings of the Bats are in fact, 

 nothing else than these extremities, in which all the bones, 

 those of the fingers particularly, have become very long, and serve 

 to sustain a prolongation of the skin of the flanks, just as the 

 whale-bones of an umbrella serve to sustain the silk or cotton 

 of which it is made. (Plate 2. fig. 3. a. the humerus, b. the 



fore arm. c. the thumb. d. the other fingers.} 



8. These organs are not designed for aerial locomotion alone, 

 like the wings of birds : when folded, they also serve the animal 

 for creeping or suspending itself from some projecting body, 

 (Plate %,fig. 2 ) and, for this purpose, they have a free thumb, 

 which is short and armed with a hooked nail, like that of most 

 other mammals, while the rest of their fingers, which are 

 elongated beyond measure, lose their last phalanges as well as 

 the nails, and are enveloped in a fold of skin, which extends 

 from the sides of the neck to the posterior extremities, or even to 



6. AreTHl the QMjiroptera equally well organised for flight? How is this 

 family divided? -"IRniat are the organic characters of the tribe of Bats ? 

 What are the characters of the tribe Galeopithecus ? 



7. In what do Bats resemble birds ? In what do the Bats differ from other 

 mammalia ? How do the wings of Bats differ from the anterior extremities 

 of the mammalia? 



8. Do the wings of Bats serve any other purpose than that of locomotion? 



