MAMMALIA 



325 



The different forms are distinguished chiefly by the number of the movable 

 bands of "scutes" between the anterior and posterior shields. The Uttle 

 Chlamydoph'orus, of about 5 inches in length, has no movable bands at all, 

 the series of plates being uniform and continuous even to the neck. The con- 

 spicuous external ears so prevalent among the armadillos are also absent. 

 Tolypcu'tcs can roll itself up into a ball and be protected by its armor, or 

 roll away from its enemies. Its walking is digitigrade and it is called 

 "pig-footed." Armadillos are omnivorous, and one species {Das'ypus 

 sexcinc'tiis) is especially fond of carrion, burrowing up to a carcass lilce bee- 

 tles. The limbs of armadillos are short, powerful, and cla\\ed, enabling 

 them to dig rapidly in the ground. 



Fig. 265. — Nine-banded armadillo (Das'ypus novenicinc'lus). (Liitken.) 



Order IV. Sire'nia. — These are dark-colored, sparsely haired 

 or bristly, toothed, herbivorous mammals. The elongated 

 snout of the whale is replaced by large movable lips for grasping 

 the food, which consists of seaweed and other aquatic plants. 

 External ears and hind limbs are absent. The anterior limbs 

 are flipper-like, but more flexible than those of the whale, and 

 the mother sometimes holds the young under her arm. The tail 

 is horizontal. Sirenia grow to a length of 9 or 10 feet. They 

 have two sets of heterodont teeth. 



The dugong (Fig. 266) is sparsely covered with stout hairs. 

 The thick skin is underlaid with blubber. It is found on the 

 east coast of Africa, in the Indian Ocean, and the north coast of 

 Australia, and in the Red Sea. 



The manatee is found on the Atlantic coast of South America 

 and of Africa, and in the mouths of the large rivers of these 

 countries. The blubber in the manatee differs from that of the 

 whale in that it has no free oil. 



Steller's sea-cow, the recently extinct Rhyti'na, was found in 

 herds in Behring Sea. It reached a length of 20 to 30 feet. The 

 flesh was good for food, and the hide and oil of value. 



