454 THE ANATOMY OP VERTEBKATED ANIMALS. 



III. The Cheiroptera. — The Cheiroijtera may be re- 

 garded as exceedingly modified Insectivora, hr.ving their 

 nearest ally in Galeopithecus. 



They possess one or two pair o£ pectoral teats ; and the fore 

 limbs are very long, some of the digits particiilarly being 

 immensely elongated. There is a patagium, or expansion 

 of the integument, iinitiug the fore limbs with the body, 

 and extended, as a membranous web, between the elongated 

 fingers. Of these the third, fourth and fifth, and very 

 frequently the second, are devoid of nails. The pollex 

 always has a claw-like nail. When the animal is resting 

 upon the ground, the thigh is twisted upwards and back- 

 wards, in such a manner, that its extensor face looks 

 forwards, and its flexor face backwards. In consequence 

 of this the knee looks upwards and backwards, and the 

 toes are turned backwards and slightly outwards. Under 

 the same cii-cumstances, all the digits of the manus are 

 flexed upon their metacarpal bones ; and the £oIded-up wing 

 rests against the side of the body, whilst the pollex, with 

 its claw, is extended forwards. In this position the animal 

 shuffles along, with considerable rapidity; hauling itself 

 forward by the claws on the pollices, and shoving itself 

 along, by extending the hind limbs. 



The favourite attitude of a Bat, when at rest, however, 

 is that of suspension by the claws of one or both legs, with 

 the head downwards, and the patagium folded over it like a 

 cloak. The most active movement of the Bat is efi"ected by 

 flight, the fore limbs being extended, and the patagium, 

 which they support, playing the part of the feathers of a 

 bird's wing. 



The cervical vertebrae are remarkably large in proportion 

 to the others, but, as in the rest of the vertebral column, 

 the spinous processes are very short. The ribs are long 

 and cui-ved, so as to inchide a relatively capacious chest. 

 The manubrium of the sterniim is very wide, and the 

 middle of its under surface raised into a crest. In the 

 lumbar region, the vertebral column is bent, so as to be 

 concave forwards and to describe almost the quarter of a 



