386 



CLASSIFICATION OF VERTEBRATES. 



ORDER III. CHIROPTERA. 



Flying mammals, in which the anterior limbs are modified 

 into supports for the membranous wings ; dentition complete, 

 the canines strong, the molars buno-lophodont ; the total teeth 

 never exceeding t %, c \, p %, m f ; mammae pectoral ; testes 

 abdominal or inguinal ; placenta discoidal, deciduate. 



The bats must be regarded as highly specialized offshoots 

 from the insectivores, with which they closely agree in all 

 essential points except the development of wings. These last 



Fig. 361. Skeleton of bat, after Brehm. 



are membranous folds, supported upon a bony framework com- 

 posed of the modified fore limbs and extending back to the 

 hind legs, while an interfemoral membrane may or may not 

 include the tail when this is developed. Muscles to move the 

 wing are attached to the sternum, which develops a keel similar 

 to that of the birds. The modifications in the fore limbs con- 

 sist in an enormous lengthening of the digits with the exception 

 of the pollex, which remains more normal, and may terminate 

 with a claw. 



The bones are very light, being slender, with large marrow 

 cavities ; the skull varies considerably, and usually possesses a 



