FLYING MAMMALS 81 



rather capacious, to allow room for the large heart and 

 lungs ; and the sternum, or breast-bone, is keeled like that 

 of a bird to supply more surface for the attachment of still 

 further wing muscles. 



Upon this light and airy framework is stretched a flexible, 

 leathery, nearly hairless membrane, which is really a con- 

 tinuation of the skin of the mouse-like body. Enveloping 

 all the bones of the arms and hands, it extends to the hind 

 legs, and in some cases includes the tail, being further sup- 

 ported by attachment to the heels. It is by means of this 

 rudder-like tail, similar to that of a bird, that the Bat is able 

 to make its rapid evolutions. 



There are two groups of Bats ; the insectivorous 

 includes all those of Europe and most of those of America, 

 as well as portions of Asia and Africa ; the frugivorous are 

 chiefly found in the South-east of Asia. The tail of the 

 animal differs according to the group. Fruit-eating Bats 

 have no need for the particularly rapid movements so 

 desirable in the chase of insects upon the wing, and conse- 

 quently they usually possess no tail membrane, which in 

 Bats generally is long or short or absent altogether, according 

 to the habits. Where the tail ends in a hard tip it bears 

 more than a slight analogy to the prehensile tail of a monkey, 

 and renders some assistance in terrestrial locomotion. 



The short thumb is never inclosed in the wing membrane 

 and renders no aid in flight, but is furnished with a strong 

 curved claw, by means of which the Bat can suspend itself 

 head downwards when it wishes to rest. 



The hind limbs terminate in perfectly formed feet, similar 

 to those of ordinary small quadrupeds, which with the thumbs 

 of the anterior limbs, and in some cases the hard-tipped tail, 

 are used in creeping and climbing. The Bat cannot walk 

 along the ground with facility, awkwardly jerking forward 

 first one side of the body and then the other ; but it can 

 run with considerable celerity. It is a common but quite 

 erroneous notion that Bats cannot easily rise from the 

 ground, but must throw themselves into the air from an 

 elevation. Most species can swim if necessity compel them, 

 but they have no liking for water. 



Another common error is expressed in the simile ' as 



7 



