(ESOPHAGUS, STOMACH, AND INTESTINE 343 



The psalterium is the latest to be differentiated both phylo- 

 genetically and ontogenetically, and is rudimentary in the Tragu- 

 lidse. In Camels the rumen gives rise to two masses of gland- 

 containing outgrowths, known as " water-cells " : the latter are 

 separated from one another by septa and provided with sphincter- 

 like muscles. In the Cetacea (Fig. 251, c and D) and Hippo- 

 potamus, the stomach is divided into several chambers, and 

 various other modifications in form and structure are met with 



FIG. 252. STOMACH OF SHEEP. (From Oppel, after Cams and Otto.) 

 a, oesophagus ; b, c, d, the three subdivisions of the rumen, marked off from one 

 another by the folds e and/; g, reticulum ; h, cesophageal groove ; i, psalte- 

 rium ; k, aperture leading from the psalterium into the abomasum (I, m) ; n, 

 pyloric valve ; o, duodenum, 



amongst Mammals. Thus in the Kangaroo, for instance (Fig. 

 251, B), the walls of the stomach are curiously folded, and in the 

 blood-sucking Bat, Desmodus, the pyloric region gives rise to a 

 caecum two-thirds as long as the whole intestine. 



The small intestine is usually long, and varies more as to rela- 

 tive length and diameter in domesticated than in wild forms : its 

 first part, as in Birds, usually forms a duodenal loop. 



The large intestine, which is made up of a varying number of 

 coils, usually reaches a great length, and its diameter is much 

 greater than that of the small intestine : these two portions are 



