MAMMALIA 389 



Section C. Ungulata (Hoofed Mammals) 



This immense assemblage of specialized forms includes: two orders 

 of extinct mammals already dealt with, Condylarthra and Ambly- 

 poda; four orders of present-day terrestrial mammals, Artiodactyla, 

 Perissodactyla, Proboscidia, and Hyracoidea; and one order of marine 

 mammals, Sirenia. The Ungulates are on the whole the most highly 

 specialized of terrestrial mammals, just as the Cetacea are the most 

 highly specialized of aquatic mammals. 



Order 10. Artiodactyla (Even-Toed Ungulates). — The mam- 

 mals of this group are: swine, hippopotami, peccaries, camels, deer, 

 moose, elk, giraffes, pronghorns, cattle, buffalos, gnus, antelopes, 

 gazelles, yaks, sheep, ibex, goats, and many other less well known types. 

 It is a major assemblage of animals, whose size on the average is large. 

 They are purely terrestrial, though some of them are mud-loving; 

 for the most part they are cursorial, though some are heavy-bodied 

 and not very fleet of foot. They have hoofs on two or four toes. The 

 stomach usually has several chambers in adaptation to a purely 

 herbivorous diet. 



Group 1. Suina {Swine-like Ungulates). — This group consists of 

 three families, represented respectively by the hippopotamus, swine 

 proper, and peccaries. The hippopotamus (Fig. 199, A) is a large 

 heavy-bodied aquatic "hog," with four hoofs on each foot. It is 

 native of Africa, as is also the pigmy hippopotamus, a dwarf species 

 found in Liberia. The swine proper include the European wild hog 

 (Fig. 199, B), the wart hog, and several other types. The domestic 

 varieties of hog have been derived from several wild species. The 

 peccaries are swift, cursorial, hog-like creatures, that run in large 

 packs, and on account of their sheer numbers, are said to be very 

 dangerous to meet. 



Group 2. Ruminantia (Ruminants). — These ungulates "chew their 

 cud," by which is meant that they swallow their food rapidly and 

 afterwards regurgitate it into the mouth for further mastication. 

 Three assemblages of these forms are distinguished: A, Tragulina 

 (Mouse Deer); B, Tylopoda (Camels, Lamas); C, Pecora (Deer, 

 Antelopes, Oxen, Giraffes, Goats and Sheep). 



The chevrotanis or mouse deer are intermediate between the swine 

 and the ruminants, and are the most primitive of the ruminants. 

 The camels (Fig. 199, C) are a small group of well-known types, con- 



