8o BATS 



with a nimbleness that the human eye can only follow with 

 difficulty. 



The accompanying illustration of the skeleton of a Bat, 

 together with the figures in Coloured Plate IV., showing 

 open and closed wings, will assist to make plain the detailed 

 description of the chief points of its structure. 



Most of the Bats possess a full complement of teeth, the 

 four canines being large and sharp ; the incisors vary in 

 number, and still more in their proximity to each other. 

 Comparing the bones of a Bat's wing with the human hand 

 and arm, we are at once struck by their exaggerated length 

 for an animal that is often only one and a half inches long, 



SKELETON OF THE MOUSE-COLOURED BAT. 



and only in a few species exceeds in size a full-grown rat. 

 The most elongated bones are those of the hand, a feature 

 which is far more marked than in the case of the fingers. 

 The fingers cannot be closed for grasping, and except the 

 action of beating they are capable of movement only to 

 open the wing, or to fold it up against the side of the 

 body. 



Being a flying mammal, the body must necessarily be 

 designed for lightness, and to this end the bones are not 

 filled with marrow, but with air. The ribs are flattened. 

 There is considerable solidity in the shoulder girdle, where 

 the greatest strength is required, and here are attached the 

 great muscles which operate the wings. The thorax is 



