454 ZOOLOGY 



the whale-bone whales. The former include the dolphins, por- 

 poises, grampuses, narwhales, sperm whales, and beaked whales. 

 The right whales, the hump-backed whale, the gray whale, the 

 finback whale, and the sulphur bottom whale lose their embry- 

 onic teeth and produce whalebone. Food is taken with the 

 mouth open and the water is forced out through the whale-bone, 

 leaving the "catch" in the mouth. 



Order Artiodactyla (even-toed). — These, are hoofed animals 

 with toes reduced to four or two. The third and fourth toes 

 persist and bear the weight of the animal, and the second and 

 fifth, if present, may or may not touch the ground. The 

 mammae are distributed along the entire abdomen (hog) or are 

 confined to the pelvic region (ox). 



This is a splendid group containing some of man's most 

 valuable food animals. ' Included in it are cattle, sheep, goats, 

 antelopes, elk, deer; the giraffes; the camels and llamas; the 

 hippopotami; and the hogs and peccaries. The ox, sheep, goat, 

 deer, and giraffe are ruminants (see p. 445). 



The chief native American forms are llama, elk, moose, 

 black-tailed deer, pronghorn antelope, Rocky Mountain goats, 

 bighorn, musk ox, and bison. The bison was formerly one of the 

 most abundant of. our American ruminants. Now there are a 

 few in captivity and fewer still wild. Most of these forms are 

 capable of domestication, because of their tractable disposition 

 and their feeding habits. They are very valuable both for 

 their hides and their food products. In addition to the flesh 

 foods, milk and its products of butter and cheese are among the 

 most prized of human foods. Milk, as are eggs, is a complete 

 food; that is, it contains all the constituents, both organic and 

 inorganic, necessary to support growth and development, as is 

 shown by the fact that it is the sole supply of food for the 

 young immediately after birth. 



Order Perissodactyla (odd-toed). — These are hoofed animals 

 characterized by the fact that the weight of the body rests on the 

 third or middle toe, the others being more or less reduced. The 

 stomach is simple. There is no proboscis. The mammae are 

 few and confined to the pelvic region. The most common 

 examples are the horse and its allies, in which the third is the 



