450 THE MAMMALS 



have gnawing teeth, but there are two rows of these teeth rather than a 

 single row as in the rodents. Also, detailed seriological studies have been 

 made of the blood of the rabbits in comparison with the rodents, and the 

 results of these tests indicate that the relationship of the two groups is not 

 close enough to warrant their inclusion in one order. 



Order — Edentata 



This order name means without teeth. Some have small jaw teeth, 

 but they have no enamel and no roots. 



The Armadillos. The skin of the armadillo bears bony plates that 

 make this one of the few vertebrates that have an exoskeleton. When 

 the armadillo rolls itself up into a tight little ball, it is about as well pro- 

 tected as the tortoise. Food consists primarily of insects and the stout 

 legs and sharp claws of the armadillo are perfect equipment for digging 

 the insects out of the ground. 



The Sloths. These strange creatures, somewhat like longhaired mon- 

 keys in appearance, are found in the jungles of Central and South Amer- 

 ica. They spend most of their lives hanging upside down from the 

 limbs of trees and possess long, curved claws that can be hooked over 

 the limbs for support. Their food consists primarily of leaves which 

 furnish them nourishment and also sufficient water so that they do not 

 have to descend to drink. When one is placed on the ground it makes 

 a ludicrous sight as it awkwardly pulls itself along in this unaccustomed 

 position. 



The Ant Bears. These animals live primarily on ants and termites. 

 They have powerful legs and claws to dig open the nests and a long 

 sticky tongue which they put down in the opened nest. When the insects 

 are stuck to it the tongue is withdrawn into the mouth and the insects 

 are swallowed. 



Order — Primata 



The most intelligent of the mammals are included in this order. 

 The cerebral hemispheres are very large, and the surface is greatly 

 convoluted. These are features which are correlated with great mental 

 capacity. Instead of claws or hoofs, they have nails on the tips of their 

 fingers and toes. Most of them are arboreal animals with their hands 

 and feet adapted for grasping, a characteristic which enables them to 

 swing from limb to limb. This grasping ability also makes them very 

 adept at handling things, and the hands rather than the mouth are used 

 for picking up many objects. The eyes of primates are on the front of 



