OF THE UNITED STATES 425 



these distinctive characters presented on the part of the teeth in 

 rodents, they offer, as a whole, many other interesting and in- 

 structive anatomical structures and physiological functions. 

 The arboreal squirrels have already been touched upon in an- 

 other chapter; the cursorial Hares and Rabbits, are terrestrial 

 types, although the Water hare found in Alabama (Lepus aqua- 

 ticus) swims well. Some of the Mice are greal jumpers, and their 

 organization has become tilted to meet the surprising agility 

 which they possess. Many rodents are almost typically fossor- 

 ial, as the Moles and many others; while such forms as the Beav- 

 ers and Muskrats are essentially of a natatorial habit. 



In describing the mouth in the Rodentia, Sir William H. 

 Flower has remarked that it is " divided into two cavities com- 

 municating by a constricted orifice an anterior, containing the 

 large incisors, and a posterior, in which the molars are placed, 

 1he hairy integument of the face being continued inwards behind 

 the incisors. This evidently prevents substances not intended for 

 food getting into the mouth, as when the animal is engaged in 

 gnawing through an obstacle. In the Hares and Pacas the in- 

 side of the cheeks is hairy, and in some species, as in the Pouched 

 Rats and Hamsters, there are large internal cheek pouches, lined 

 with the hairy integument, which open near the angles of the 

 mouth and extend backwards behind the ears; in the Xew- World 

 Pouched Rats (Geomyidw) the pouches open externally on the 

 cheeks." 



Speaking of the Hares, it may be said that we have in this 

 country many species and subspecies of them, all belonging to 

 the family Leporidw ; but we have no true Rabbits, a name, which, 

 by custom, has only been applied to the smaller variety of our 

 Hares, as they so closely resemble the true Rabbits of the Old 

 World. These latter by habit are gregarious, and are found in 

 the open country, where they make burrows to live in. Their 

 young are also born blind and naked, which is not the case with 

 the Hares, which last are found only in cover of some sort or 

 other, and never burrow, and are solitary by nature. The two 

 species are also very different in appearance. Lepus cuniculus 

 is the common wild rabbit of Europe, while our most common 

 Cotton-tail is the L. s. sylvaticus, an animal so well known as to 

 require no special description. 



The Jackass Rabbits are large Hares found in immense num- 

 bers in the West and Southwest, and they afford excellent sport 



