XIII 



PHYLUM CHORDATA 



555 



cud. In this process the sodden food is returned in rounded 

 boluses from the rumen to the mouth, and there undergoes 

 mastication. When fully masticated it is swallowed again in a 



FIG. 1211. Stomach of Ruminant opened to show the internal structure, a, ossophagus; 

 b, rumen ; c, reticulum ; d, psalterium ; e, abomasum ; /, duodenum. (After Flower and 

 Lydekker.) 



semi-fluid condition, and passes along the groove into the reti- 

 culum, or over the unmasticated food contained in the latter 

 chamber, 5 ,to strain through between the leaves of the psalterium 

 and enter the 

 abomasum, where 

 the process of 

 digestion goes on. 

 In some Rumi- 

 nants the psalter- 



ium is wanting. 



In the Camels 

 (Fig. 1210, G) the 

 stomach is not so 

 complicated as in 

 the more typical 

 Ruminants, there 

 being also no dis- 

 tinct psalterium, 

 and the rumen 

 being devoid of 

 villi ; both the 



rumen and the re- 



tlCulum have COn- 



4- A ~4-\* 4-1^ 

 neCteQ Wit!! tnem 



a niimliprnf nnnr-Vi 

 anumoeroi pOUCn- 



like diverticula 

 (w. z.), the openings of which are capable of being closed^by 

 sphincter muscles ; in these water is stored. In the Cetacea the 

 stomach is also divided into compartments. In the Porpoise 



FIG 1 2 12. Diagrammatic section of the stomach of the 

 Porpoise, a, oesophagus ; b, left or cardiac compartment ; 

 c ? m iddle compartment ; d and e, the two divisions of the 

 right, or pykmc compartmentl; /, pylorus ; g, duodenum, 

 dilated at its commencement ; h, bile-duct. (After Flower 

 and Lydekker.) 



