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ANIMAL BIOLOGY 



The group Cheiroptera, or bats, have fore limbs modified 

 into wings. The second, third, fourth and fifth digits of 

 the fore feet are enormously lengthened to form the sup- 

 port of a thin membrane stretched between them and 

 extending from the fifth digit to the hind leg and thence 

 usually to the tail. The first digit, or thumb, is short, 

 and modified into a sort of hook. Our common bats live 

 mainly upon insects which they catch while flying during 

 the night or toward evening. Many of the bats of the 

 old world are fruit eaters, and certain bats of Mexico and 



FIG. 169. Skeleton of a bat. 



South America live by sucking the blood of mammals. 

 They attack their victims while the latter are asleep; and, 

 after making incisions with their very sharp teeth, quietly 

 suck the blood. Many bats, but by no means all, have 

 very small eyes. While the popular notion that bats are 

 blind is incorrect, these animals when blinded may fly 

 about a room full of objects or even strung with wires 

 without encountering any of the obstructions. They 

 apparently have other very acute senses which warn them 

 of the proximity of obstacles to their flight. Bats gener- 



