CLASS MAMMALIA. MAMMALS 



487 



Elephant 11 feet high 



Blue whale 105 feet 

 Figure 359. Relative size of a blue whale, the largest living animal, and an African elephant. 



disappear from the sea, unless protected by 

 law, because modern ships go out to hunt 

 these animals, equipped with airplanes, 

 radar, whale guns, and other refined ap- 

 paratus. 



Sea cows 



Sea cows differ considerably in structure 

 from whales. Their bones are heav)', en- 

 abling them to remain on the bottom; the 

 teeth are broad and crushing; the lips are 

 large and movable and are used to seize 

 seaweeds and other water plants upon which 

 they feed; the forelimbs are flexible flippers; 

 and the tail is rounded and not notched as 

 in whales. The Florida manatee (Fig. 

 352B), is a genus of "sea cow." The sea 

 cows and manatees probably account for 

 some of the tales of the so-called mermaids. 



Elephants 



Elephants are the largest land animals, 

 weighing as much as 14,640 pounds. The 

 two species of living elephants are the Asiatic 

 elephant (Fig. 356D), and the African 

 elephant (Fig. 356C). Both species are 

 covered by a thick loose skin with a thin 

 coat of hair; they have long, muscular pro- 

 boscises (trunks) with nasal openings at 

 the tips; they are provided with tusks which 

 are elongated incisors; they possess small 

 eyes, small tails, and enormous ears, and are 

 without canine teeth. The skull is massive, 



due to thick bones containing air spaces; 

 and the grinding teeth are very large and 

 possess complicated ridges. 



Hoofed mammals 



Hoofed mammals are divided into those 

 with an odd number of toes and those with 

 an even number of toes. Horses, tapirs, and 

 rhinoceroses have an odd number of hoofed 

 toes, the axis of symmetry passing through 

 the third digit. None is native to the United 

 States, but many remains of extinct species 

 have been found in this country. The tapirs 

 occur in Central and South America, and in 

 Sumatra, Java, and the Malay Peninsula. 

 The American tapirs have long, prehensile 

 noses (Fig. 356E). 



The majority of the big game animals be- 

 long to the even-toed hoofed mammals. 

 The axis of symmetry passes between digits 

 3 and 4. Here belong the peccaries, pigs, 

 hippopotami, camels, llamas, hollow-horned 

 ruminants, pronghorn antelopes (Fig. 356- 

 F), giraffes, and deer. The term ruminant 

 has been given to the animals belonging to 

 the camel, deer, giraffe, pronghorn antelope, 

 and ox families, since they ruminate or chew 

 their cud. The food of these animals is 

 swallowed without sufficient mastication; it 

 is later regurgitated in small quantities and 

 thoroughly chewed. A typical ruminant pos- 

 sesses a stomach consisting of 4 chambers 

 (Fig. 360). 



