RUMINANTIA DIGESTIVE SYSTEM. 



869 



is united to the anterior extremity of the rumen. The inferior convex curvature 

 occupies the epigastric region; 

 the superior concave one is 

 partially related with the small 

 curvature of the third com- 

 partment. The left extremity 

 is separated from the rumen 

 by a fissure, in which runs the 

 inferior artery of the reticu- 

 lum. The right forms a round 

 cul-de-sac, and is related with 

 the base of the fourth com- 

 partment. The internal sur- 

 face of the reticulum is divided 

 into polyhedral alveoli or cells, 

 by folds of the mucous mem- 

 brane. These folds are stud- 

 ded with papillae, and serrated 

 at their edges ; in the alveoli 

 are secondary ones, where 

 mucous follicles open. The 

 reticulum communicates with 

 the left sac of the rumen, the 

 oesophagus, and third com- 

 partment. The communica- 

 tion with the two latter is by 

 the oesophageal canal, a con- 

 tinuation of the oesophagus, 

 which commences at the car- 

 diac orifice, passes along the 

 roof of the reticulum, and 

 enters the third compartment 

 by a circular opening. Its 

 sides consist of two movable 

 lips, the ceso2?hageal pillars, 

 which are continuous with the 

 muscular wall of the oesopha- 

 gus, and are attached by one 

 border to the suj^erior wall of 

 the reticulum, the other being 

 free. The latter get gradually 

 thicker and more projecting 

 as they reach the opening of 

 the third compartment. At 

 the entrance into the rumen 

 is a sort of valve, formed by 

 the attachment of the pillars 

 to its walls. The mucous 

 membrane of this canal is wrinkled on its free surface, but on the interior 

 resembles that of the oesophagus, being white, and longitudinally folded. At 



2 B 



Compartments of a Kumiuant Stomach, laid open. A, 

 Rumen— a, a, a, a, Pillars ; b, b, Papillae ; c, (Esophageal 

 orifice. B, Reticulum— a, a. Alveoli ; b, (Esophageal 

 caual. C, Psalterium— a, Hooked papillae ; 6, Valve at 

 orifice leading to abomasum ; c, d, e, f, Leaves graduated 

 from large to small. D, Abomasum— «, a, Eolds of 

 mucous membrane ; i, Pyloric orifice ; c, Duodenum. 



