VERTEBRATA 



193 



The toes, and one or two of the fingers, are armed with 

 hooked nails. The clavicles are remarkably long, and 

 the sternum is of great strength ; but the whole skele- 

 ton is extremely light, though not filled with air, as in 



\ ,. 



FIG. 185. Skeleton of a bat. 



birds. The eyes are small, the ears large, and the sense 

 of touch is very acute. The favorite attitude of a bat 

 when at rest is that of suspension by the claws, with 

 head downward. They are all nocturnal. 



9. Primates, the head of the kingdom, are character- 

 ized by the possession of two hands and two feet. The 

 thigh is free from the body, and all the digits are fur- 

 nished with nails, the first on the foot enlarged to a 

 "great toe." Throughout the order, the hand is emi- 

 nently or wholly prehensile, and the foot, however 

 prehensile it may be, is always a locomotor organ (Fig. 

 IQ2). 54 The clavicles are perfect (Fig. 317). The eyes 

 are situated in a complete bony cavity, and look for- 

 ward. There are two sets of teeth, all enameled ; and 

 the incisors number four in each jaw (Fig. 233). They 

 include the lemurs, monkeys and apes, and man. 



The lemurs are covered with soft fur, have usually 



a long tail, pointed ears, foxlike muzzle, and curved 



nostrils. They walk on all fours, and the thumb and 



great toe are generally opposable to the digits: The 



DODGE'S GEN. ZOOL. 13 



