540 



ZOOLOGY 



SECT. 



up into numerous longitudinal leaf-like folds. The abomasum 

 (e), smaller than the rumen, but larger than the reticulum, has 

 a smooth vascular and glandular mucous membrane. The oeso- 

 phagus opens into the rumen close to its junction with the 

 reticulum. The herbage on which the Ruminant feeds is swal- 

 lowed without mastication, accompanied by copious saliva, and 

 passes into the rumen and reticulum, where it lies until, having 

 finished feeding, the animal begins ruminating or chewing the 

 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 

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

 culum, or over the unmasticated food contained in the latter 

 chamber, to strain through between the leaves of the psalterium 



I 



FIG. 1130. Stomach of Ruminant opened to show the internal structure, a, oesophagus 

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

 Lydekker.) 



and enter the abomasum, where the process of digestion goes on. 

 In the Camels (Fig. 1129, G) the stomach is not so complicated 

 as in the other Ruminants, there being no distinct psalterium, 

 and the rumen being devoid of villi. Both the rumen and the 

 reticulum have connected with them a number of pouch-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. 1131) the oesophagus (a) opens into a spacious 

 crop (l>), the cardiac compartment of the stomach, with a smooth, 

 thick, mucous membrane. This is followed by a second chamber 

 (c) of considerably smaller dimensions with a glandular mucous 

 membrane, which is thrown into a number of complex folds. A 

 long and narrow third, or pyloric, compartment (d,e) follows upon 

 this, terminating in a constricted pyloric aperture, beyond which 

 the beginning of the intestine is dilated into a bulb. 



