384 CLASSIFICATION OF VERTEBRATES. ' 



seven to nine movable armor bands. Tatusia novemcincta is the only arma- 

 dillo entering the U. S. Chlainydotherium from the pleistocene of Florida 

 and Patagonia stands nearest the glyptodonts. Peltephilus, eocene of 

 Patagonia. 



FIG. 360. Nine-banded armadillo, Tatusia novemcincta, from Liitken. 



ORDER II. INSECTIVORA. 



Small plantigrade mammals, usually with five toes armed 

 with claws ; carpals and tarsals usually in linear series ; denti- 

 tion complete, the incisors never less than two ; canines little 

 differentiated and weak ; molars bunodont or lophodont, the 

 cusps acute ; clavicles almost invariably present ; brain small, 

 cerebrum without convolutions ; placenta deciduate, discoidal. 



The insectivores owe their name to the fact that the major- 

 ity feed upon insects or other small invertebrates. They are all 

 small, and the structure points to a low stage of organization. 

 The body is covered with fur, and spines are not infrequently 

 developed. The milk dentition is lost at an early date, and 

 rarely is functional. The canine teeth are not sharply differen- 

 tiated from the incisors or premolars, and the latter are sharp 

 sectorial. The upper molars have three or four cusps. The 

 testes are internal, and are never enclosed in a scrotum ; the 

 uterus is bicornuate. In a few genera vertebral intercentra 

 occur in the dorsal region, a condition not paralleled in other 

 mammalia. Among the more superficial but still very charac- 

 teristic features is the prolongation of the muzzle far beyond 

 the lower jaw. 



Most of the order are nocturnal burrowing animals, only a 

 few being aquatic or arboreal in habits. In external appearance 

 they resemble the smaller rodents ; but in structure they are 

 more like the bats, with other resemblances to the polyproto- 



