4 Contents 



Order Ungulata. Hoofed Mammals 57 



Family Cervidas. Deer, Moose, Elk, Caribou 58 



Key to the Genera 59 



Key to the Species 59 



Family Bovidas. Bison, Oxen, Sheep, etc 86 



Order Glires. Gnawing Mammals 97 



Key to the Suborders and Families , . . . .98 



Family Sciuridae. Squirrels, Wood chucks, etc 98 



Key to the Genera 99 



Key to the Species 99 



Subfamily Pteromyinas. Flying Squirrels 102 



Subfamily Sciurinae. Squirrels, Chipmunks, etc 108 



Subfamily Marmotinae. Prairie Squirrels, Woodchucks, etc. . 137 



Family Castoridas. Beavers 158 



Family Muridae. Rats and Mice 171 



Key to the Genera 171 



Key to the Species 173 



Subfamily Murinae. Old World Rats and Mice 176 



Subfamily Cricetinse. White-footed Mice, Cotton Mice, etc. . 183 



Key to the Species 183 



Subfamily Neotominae. Wood Rats 204 



Subfamily Microtinae. Meadow Mice or Voles, Lemming 



Mice, and Muskrats 208 



Key to the Subgenera and Species of if ^cro/M5 213 



Family Geom5adas. Pocket Gophers 239 



Family Zapodidas. Jumping Mice 246 



Subfamily Zapodinas. American Jumping Mice .... 246 



Family Erethizontidae. American Porcupines 253 



Subfamily Erethizontinae. American Porcupines . . . .254 



Family Leporidae. Hares and Rabbits . . . . 259 



Key to the Genera 261 



Key to the Species 261 



Order Fer^e. Flesh Eaters . . 275 



Key to the Families 277 



Family FeHdag. The Cats 277 



Subfamily Felinae. Panthers, Lynx, Wild Cat, etc. . . .279 



Key to the Genera 279 



Key to the Species 279 



Family Canidae. Wolves and Foxes . 296 



Key to the Genera 298 



Key to the Species 299 



Family MusteHdae. Otters, Minks, Weasels, Skunks, Badgers, etc. 327 



