264 VERTEBRATA 



States is the Virginia opossum found in nearly every 

 state. The young varying in number from six to twelve 

 are naked, blind, and about half an inch long at birth, 

 when the mother by means of her fore paws places them 

 in her pouch. Here they remain several weeks constantly 

 attached to the teats through which the mother pumps 

 the milk into their mouths. 



Ant-eaters (Edentata). This order is so named be- 

 cause some of the species have no teeth. The armadillos, 

 remarkable for their covering of bony plates, inhabit 

 South America and southern North America, while the 

 ant-eaters dwell in South America, Asia, and Africa. 

 The Sloths live in South America only. 



Sea cows (Sirenia). The members of this order are 

 characterized by the absence of hind limbs and the pres- 

 ence of paddle-like fore limbs adapted for an aquatic life. 

 The manatee is the only representative in our country. 

 It swims in the rivers of Florida. The fact that the flipper- 

 like fore limbs contain the same bones present in the ter- 

 restrial mammals, indicates that the ancestors of the 

 Sirenia were land mammals. 



Whales, Dolphins, and Porpoises (Cetacea). These, like 

 the Sirenia, are entirely aquatic, and with few exceptions 

 live in salt water only. They are characterized by the 

 absence of hair and hind limbs, though in some species 

 rudiments of the latter are found beneath the skin, indi- 

 cating that the whales have descended from land animals 

 with two pairs of limbs. The toothless, or baleen whales, 

 are valuable both for oil and whalebone. The largest 

 species, the sulphur-bottom whale of the Pacific, attains a 

 length of ninety-five feet, One individual will yield three 



