4*20 



ANATOMY OF VERTEBKATES. 



and its parts, as compared with the body, in a few species of the 

 different families of Marsupialia : — 



§ 226. Alimentary canal of Rodentia. — In relation to the de- 

 gree of comminution of 

 the food and in continua- 

 tion of the character of 

 the fauces the oesophagus 

 is narrow in all Rodents 

 and is usually continued a 

 short way into the abdo- 

 men before opening into 

 the stomach. The posi- 

 tion of the cardia is at or 

 near to the middle of the 

 upper curvature (fig. 317, 

 /, Rat, fig. 318,/, g, Vole) 

 as in Marsupials, and the 

 modifications of the ali- 

 mentary canal in relation 

 to the nature of the food 

 are, also, manifested chiefly 

 in the caecum. The left 

 end of the stomach com- 

 monly projects beyond the 

 pylorus, fig. 317, d, fig. 

 318, b : and it is not unusual to find both ' blind sacs ' marked 

 off by transverse constrictions from the mid-part of the cavity, 

 fig. 317, b. The oesophageal epithelium is usually continued 

 upon the inner surface of the cardiac compartment, ib. a. In 

 the Porcupine, which shows well this tripartite type of stomach, 



Intestinal canal, with proper and supplementary 

 stomachs (Mus Rattus). cxxn'. 



