MAMMALIA 



355 



The family Leporidw is represented by hares and rabbits. Formula for 



pair of upper incisors 

 This arrangement of 



the teeth: Incisors, „; molars, ^, or 28 in all. One pair of upper incisors 



2' "'"*"--> 5_5 

 is much smaller and immediately behind the other 



Fig. 288. — Faces of pocket gophers, showing pouches and incisors: 

 a, Geomys; h, Cratogeomys ; c, Thomomys. (Yearbook U. S. Dept. of Agri- 

 culture, 1909.) 



the incisors has given rise to the term Duplicidenia'ta. The soles are furred, 

 the tail short and recurved, the eyes large, and the ears long. The hind limbs 

 (Fig. 289) are longer than the fore hmbs (Fig. 290), and they "run" by 



Fig. 289. — Posterior limb of Jack-rabbit. (Mounted by students.) 



prodigious leaps. Genus Lepus contains thirty or forty species. Our 

 common forms in the United States are the "cotton-tail" (L. sylvalicus); 

 the marsh hare (L. palustris); the water rabbit {L. aqualicus), also a south- 



