MAMMALS 361 



O. saxatilis Bangs. Color pale yellowish brown, buff beneath; 

 length 182 mm.; hind foot 30 mm.: Snowy Range, Colorado. 



O. uinta Hollister. Color uniform clay, without gray; size similar 

 to O. saxatilis: Uinta Mountains, Utah. 



O. levis Holl. Color light buffy brown; length 168 mm. ; tail 10 mm. : 

 Belt Mountains, Bitter Root Mountains, Montana. 



O. taylori Grinnell. Color and size like O. schisticeps, but darker 

 and browner: Modoc County, California. 



O. schisticeps (Merriam). Color gray suffused with fulvous; top of 

 head slate-gray; length 188 mm.; tail vertebrae 9 mm.; hind foot 29 

 mm.: Sierra Nevada Mountains, California. 



O. cinnamomea Allen. Color pale cinnamon rufous, darker in the 

 middorsal region; top of head gray; similar to 0. schisticeps, but smaller 

 and lacking the slate-gray area on the head: Beaver Range, Utah, above 

 10,000 feet elevation. 



Order 9. Ungulata. — Hoofed animals. Mammals of large size 

 with I to 4 hoofs on each foot; molar teeth with broad crowns and 

 adapted to the mastication of grasses and grains : about a dozen families, 

 grouped in 2 suborders, and distributed throughout the world except 

 in the Australian region, of which 4 occur in North America and 2 

 in the United States and Canada. The order contains the most 

 important domestic animals. 



Key to the Suborders of Ungulata 



ai Number of hoofs on each foot either 2 or 4 ; even-toed ungulates .1. A rtiodactyla. 

 a2 Number of hoofs on each foot i or 3; odd-toed ungulates; no 

 native species in the United States; horses; tapirs; rhinoc- 

 eroses 2. Perissodactyla. 



Suborder Artiodactyla.- — Even-toes ungulates. Third and fourth 

 digits prolonged beyond the others and support the animal's body; 

 premolar and molar teeth usually not alike; stomach complex: about 

 300 species grouped in 2 divisions; about 40 species in the United 

 States and Canada. 



Key to the Divisions of Artiodactyla 



ai Upper incisors and canines presents i. Suina. 



a2 Upper incisors and canines absent 2. Ruminantia. 



Division i. Suina. — Pigs. Non-ruminant Artiodactyla with inci- 

 sor, canine, premolar and molar teeth in both jaws; no horns present; 

 metacarpals and metatarsals not fused; body large and robust; hairs 

 bristle-like; skin very thick: 3 families, i of which only has native 



