CHEIROPTERA. 



593 



The: Oieiroptera are cosmopolitan in their distribution, and the 

 oldest known species is from the Eocene rocks. 



The Bats are all crepuscular and nocturnal in their habits, 

 and are sometimes carnivorous, sometimes frugivorous. The 

 eyes are small, but the ears are very large, arid their sense of 

 touch is most acute. During the day they retire to caves or 

 crevices amongst the rocks, where they suspend themselves by 

 means of the short thumbs, which are provided with curved 

 claws. In their flight, though they can fly in the genuine and 

 proper sense of the term, and can turn with great ease, they 



Fig. 230. — Skeleton of Fox-bat {Pteroplis) — after Owen. 



are by no means as rapid and as active as are the true birds. 

 The tail is sometimes short, sometimes moderately long, and 

 is usually included in a continuation of the leathery patagium, 

 which stretches between the hind-legs, and is termed the " in- 

 ter-femoral membrane." The .body is covered with hair, but 

 the patagium is usually hairless,' or nearly so. Most of the 

 Bats hybemate. 



The Cheiroptera are conveniently divided into the two sec- 

 tions of the Insectivora and Frugivora, according as the diet 

 consists of insects or of fruits. 



