92 SKETCH OF THE H J STORY OF MAMMALIA. 



53.— Skull and Teeth of Canada Sand-Rat. 



as synonymous with the genus Geowys of Rafinesque, 

 and which is represented by the Sand-Rat, distinguished 

 by large cheek-pouches, which when full have an oblong 

 form and nearly touch the ground, but when empty are 

 retracted for three-fourths of their length. Their inte- 

 rior is very glandular, particularly the orifice that opens 



into the mouth. The incisors are 



4—4 



4—4' 



Fig. 53 repre- 



sents the skull and teeth of Geomys, as given by Dr. 

 Richardson: 1, 2, 3, skull, natural size, in different 



