MAMMIFEROUS ANIMALS. 



rather hands, by which the principal actions of 

 the animal are produced. 



Contrary to the hind extremities, (just describ- 

 ed,) which, in most particulars, resemble those 

 of the other qnadrumanous animals; the bones 

 of the fore arms and fingers of the Bat, (with the 

 exception of the thumb, which is short, detach- 

 ed, and armed with a hooked nail,) form thin, 

 and long continued processes ; having the inter- 

 vals between, filled up by a very fine, transpar- 

 ent, umbrageous, and sail-like membrane, which 

 extends to the muscles of the breast bone, and 

 to the hind legs and tail* thus enveloping as it 

 were, nearly the whole animal, and giving it, 

 while on the ground, incumbered as it is by its 

 folded membrane, a very unseemly and awk- 

 ward appearance, more especially when it afr- 

 tempts to walk, which it finds some difficulty in 

 accomplishing. But upon its ascent, (to effect 

 which, it is necessary to attain some point of 

 elevation,) it assumes, altogether, a new and 

 highly interesting character. For the elongated 

 fingers, acting as yards to a sail, become, at the 

 will of the animal, very widely extended ; and 

 the whole membrane throughout, thus put upon 

 the stretch, is converted by the joint action of the 

 pectoral muscles, into a beautiful pair of wings 

 of very considerable expansion, which, being ra- 

 pidly thrown into motion to preserve the animal's 

 equilibrium in the air, give to it the flitting ap- 



