1322 THE RODENTS 



are likened by Mr. O. Thomas, on account of their nearly naked skin, small eyes, 

 and peculiar physiognomy, to tiny hairless puppies. They have small heads, with 

 projecting incisor teeth, and no external ears, while the limbs and tail are of moder- 

 ate length. The eyes are almost functionless; and although the feet are fringed 

 with hairs, the yellowish skin is almost naked, save for a few sparsely scattered 

 hairs. One of the two species has three pairs of molar teeth in each jaw, while in 

 the other there are but two. 



These sand rats are entirely subterranean in their habits. Mr. Lort Phillips 

 states they throw up ' ' groups ' ' of miniature craters, which exactly represent 

 volcanoes in active eruption. When the little beasts were at work I used frequently 

 to watch them, and found that the loose earth from their excavations was brought 

 to the bottom of the crater, and sent with great force into the air in a succession of 

 rapid jerks, but they themselves never venture forth from the shelter of their 

 burrows. ' ' 



THE AMERICAN POUCHED RATS 

 Family GEOMTID^ 



The possession of large cheek pouches lined with hair, which open externally 

 to the mouth at the lower edges of the cheeks, forms the distinctive peculiarity of 

 a family of rat-like Rodents confined to the New World. The forms included in 

 the family vary considerably in external appearance and habits; its larger and bur- 

 rowing representatives being known as pocket gophers, while the smaller terres- 

 trial types are respectively termed kangaroo rats and pocket mice. In addition to 

 three pairs of molar teeth with transverse plates of enamel on their crowns, and 

 which may or may not be rooted, all these Rodents have a single pair of premolar 

 teeth in each jaw. Their skulls are characterized by the great twisting of each 

 branch of the lower jaw, and likewise by the forward extension of the cheek bone. 



POCKET GOPHERS 

 Genera Geomys and Thomomys 



The pocket gophers include large rat-like species, with burrowing habits, and 

 are characterized by their small eyes, rudimental external ears, and the equality in 

 length of their comparatively-short limbs. The whole of them are confined to 

 North and Central America. 



The common pocket gopher (Geomys bursarius] is selected for illus- 



p , . tration as the best-known representative of the group, and as being 



Gopher tne *yP e f t^ 16 genus Geomys, characterized by the presence of a deep 



groove on each of the broad incisor teeth. This species attains a 



length of from seven to eight inches from the muzzle to the root of the tail, while 



the hairy tail itself varies from two to three inches. The fur is of a soft and mole-like 



texture, and of a beautiful reddish-brown color above, becoming grayish beneath, 



while on the feet, and generally also on the tail, it is white. 



