MAMMALIA 



355 



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

 the teeth: Incisors, 2 ; molars, ^, or 28 in alt. One pair of upper incisors 

 is much smaller and immediately behind the other. This arrangement of 



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

 a, Geomys; b, Cralogeornys; c, Thomomys. (Yearbook U. S. Dept. of Agri- 

 culture, 1909.) 



the incisors has given rise to the term Duplicidenta'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 limbs (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. sylvaticus) ; 

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



