Family APLODONTIIDAE Mountain Beaver 



Guinea pig appearanee; molars plane, without infoldings of 



enamel on grinding surface 



One genus — Aplodontia 

 Family ZAPODIDAE Jumping Mice 



With elongate hind legs and tail; upper incisors grooved in 



front 



Two genera — Zapus 



J\lapaeozapns 

 Family ERETHIZONTIDAE Porcupines 



Hairs coarse, with some thickened to form quills; v^'ith four 



fingers and five toes on each side; ears short 



One genus — Erethizon 

 Order LAGOMORPHA Rabbits, Hares, Pikas 



Much like rodents, but with a pair of small incisor teeth behind 



the large upper pair 



Family OCHOTONIDAE Pikas 



No external tail; hind legs scarcely longer than fore legs 



One genus — Ochotona 

 Family LEPORIDAE Hares and Rabbits 



With a short tail; hind legs elongate 



Two genera — Lepus 



Sylvilagus 

 Order ARTIODACTYLA 



Even-toed hoofed mammals 



Family TAYASSUIDAE Peccaries 



Pig'like, but almost tailless; upper canines pointing down' 



wards, and with four upper incisors 



One genus — Pecari 

 Family CERVIDAE Deer 



Males with solid antlers, shed annually, growing from per' 



manent bases on the frontal bones; second and fifth toes 



present 



Four genera — Cervus 



Odocoileus 

 Alee 

 liangifer 

 Family ANTILOCAPRIDAE Pronghorn 



Both sexes with deciduous, one-branched horns on permanent, 



unbranched cores; orbit below horn ■ i^\ftft^^/\ 



One genus — AnUlocapra /^^ .*««?■•*. • 



479 



