ORDER CARNASSIER. 87 



bird is consequently a mere rudiment. The wing exists 

 beyond it, resting and adjusted on this extremity of the 

 limb, and consisting in its long terminal pennae ; so that in 

 fact, in the last analysis we find that the greater part of this 

 organ is composed of branches or elements belonging to the 

 epidermic system. 



In the bat, on the contrary, it is the limb itself and prin- 

 cipally the hand, which are so wonderfully aggrandized. 

 Let us imagine the hand of an ape, the solid parts of which 

 should have passed almost to a filament, and separated from 

 the carpus, like the radii of the segment of a circle, and we 

 shall have a precise idea of the hand of a bat. 



The thumb alone does not experience the same modifica- 

 tions. It remains short, free, and susceptible of the most 

 varied movements. 



Such is also the thumb of apes. As it is not employed as 

 an organ of flight by the cheiroptera, that it may preserve 

 its ordinary function, it remains in its full entirety, pro- 

 vided with its last phalanx and with its nail. 



On the other side, the four fingers, which their immea- 

 surable length changes into instruments of volitation, are 

 no longer susceptible of their original destination ; so that 

 it is with much pain and difficulty that the bats occasionally 

 employ them to move their bodies upon a horizontal plain, 

 or to hold their little ones. 



Another anomaly renders these four fingers worthy of 

 attention. They are no longer entire. They are destitute 

 of nails, and it is remarkable that the phalanx which ter- 

 minates them, and which, in other instances, always appears 

 with an impression beneath the nail, finishes exactly where 

 the nail should begin. 



The long phalanges of the bats, act as supports to their 

 wings, and seem destined to retain in a state of tension the 

 membranous substance which resists the air. This last is 

 produced in the bats by a prolongation of the skin of the 



