SKELETON OK BAT (A'^Cteris). 



CHAP TEE IX. 



Bats, — Order Chiroptera. 



In some cases there is more or less difficulty, especially when we have to take 

 extinct types into consideration, in findino- well-marked characteristics by which 

 the various orders of ilaunnals can be distinguished from each otlier. With bats, 

 however, there is no such ilifficulty, since they are sharply distinguished from all 

 other Mammals by possessing the power of trae flight, for the purpose of which their 

 fore-limbs are speciallj- modified. , We say true flight advisedly, for the reason 

 that there is a kind of spurious flight possessed bj^ certain other Mammals, such as 

 flying squirrels and flying phalangers, which is quite different from the flight of 

 bats, and does not entail any special modification of the structure of the fore-limbs. 

 True flight, like that of birds and bats, is eflfected by means of alternate upward 

 and downward strokes of the wings, and can be carried on as long as the muscular 

 power of the flyer permits. Spurious flight, like that of the flying squirrels, is, on 

 the other hand, nothing more than a prolongation of an upward or downward leap, 

 by the aid of parachute-like expansions of the skin of the sides of the body, and 



