414 



METAZOAN PHYLA 



number of these are valuable for their fur. The second suborder, 

 Pinnipedia (pin i pe' di a; L., pinna, feather, and pedis, foot), is made 

 up of marine mammals in which both the fore- and hind limbs are modified 

 to form finhke flippers. It includes such gregarious forms as the seals, 

 walruses, and sea hons, which are often found collected in rookeries on 



Fig. 283. — Feet of carnivores. A, plantigrade foot (foreleg) of a bear. B, digitigrade 

 foot (foreleg) of a cat. (From Schmeil, "Text-book of Zoology," by the courtesy of A. aiid 

 C. Black, and of Quelle and Meyer.) 



islands, particularly in the Arctic regions. The fur seal is very important 

 commercially. 



The order Rodentia (ro den' shi a; L., rodentis, gnawing) contains 

 mostly small animals characterized by the absence of canine teeth and 



Fig. 284. — Nine-banded armadillo, Dasypvs novemcinctus Linnaeus, found from Texas 

 and southern New Mexico to Argentina. From a mounted specimen. X }i. 



the great development of the incisors, which are used in gnawing. The 

 incisors continue to grow throughout life and the wearing away of the 

 soft dentine behind leaves the hard enamel at the front of the tooth 

 constantly extended beyond the rest as a sharp, cutting edge. This 

 order includes the hares, rabbits, squirrels, rats, mice, porcupines, and 



