IV. VERTLBRATA; MAMMALIA, UXC.l'LATA 



5 Hi 



The molars arc selcnodont. With few r.xrcptions Ruminants are of large size 

 and many bear horns on the frontal bones, larger in the males and may occur 

 exclusively in that sex. In the giraffes these are cones free from the frontals and 

 covered with skin. In others (Cavicornia) the horn cores fuse secondarily with 

 the frontals and are covered with a sheath of horn. Lastly, the horns are out- 

 growths of the frontal bone, in which usually the outer coats of skin and hair 

 (velvet) are soon lost and only the bone projects freely (antlers). These are 

 shed yearly, the new antler which takes its place being larger and consisting of 

 a larger number of branches or tines, thus constituting an index of age (Cervi- 

 cornia). CAMELOPARDALID.E (Devexa), giraffes, long-legged forms from 

 Africa with persistent horns; teeth frit, Gira/a, Okapia. CERVID.*:, deer, 

 deciduous horns in the male. Cervus,* common deer; Alces,* moose; Rangift i , :: 

 reindeer; MOSCHID.E, horns lacking, males with enlarged upper canines and a 

 musk gland; MoscJnis, central Asia. TRAGULID^E, primitive, Asia and Africa. 

 The CAVICORNIA include many species, some of great economic importance; 

 teeth -3-^33. BOVID.E: Bos taunts, domestic cattle, probably descended from 

 three distinct stocks (B. primi genius, aurochs, B. Lm^ifrons and B. frimlosus); 

 Bison,* including B. euro pens, bison proper, and B. americanus* our 'buffalo.' 

 Bubalus, the true buffalo of the Old World. OYID.E: Ovis arics, sheep; O. 

 in mtana,* big horn; Capra Jiircus, goat; Ovibos moschatus* musk ox. AXTI- 

 LOPID.'E: including a host of Old World forms (Antilope, Gazclla, Rupicapra 

 trains, the chamois, etc.) and Antilocapra americana* prong horn, which sheds 

 its horns, and Hoploceras montanus* Rocky mountain sheep. 



Section III. TYLOPODA, stomach without manyplies, no frontal horns, 

 diJuse placenta. Camel us, Old World camels; Auchenia lama, A. alpaca of 

 South America. 



Paleontology of the Ungulata. 



Abundant paleontological material, especially from the tertiary of our 

 western states, has cleared up many lines of ungulate descent and has shown 

 it probable that the CONDYLARTHRA of the eocene, with five-toed planti- 

 grade feet, well-developed ulna and fibula, and omnivorous dentition, formed 

 the stock from which the artiodactyles and perissodactyles descended, and 



FIG. 617. Evolution of fore foot of horse (from Wiedersheim). i, Orohippus 

 (eocene); 2, Mesohipfrus (lower miocene); 3. Miohippus (miocene) ; 4, Protohippus 

 (upper pliocene); 5, Pliohippus (pleistocene); 6, Eqitux. 



possibly carnivores and primates as well, the ungulate line extending through 

 the Amblypoda. From one group of these (PHEXACODONTIDJC) the lines of 

 rhinoceros and tapir have come, and in an almost complete scries we know the 

 ancestry of the horse. Hyracotherium (Eohippus] and Oroluppus of the eocene 

 had the fore feet four-toed (fig. 617, i); Pahcotherium and Mcsahippus (2) of the 

 lower miocene and Miohifip-ns of the later miocene were three-toed, while .\frr\- 

 hippus and Hipparion (Pliohippus, 4) of the pliocene were near the horse in 



