RUMINANTIA DIGESTIVE SYSTEM. 



369 



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

 occupies the epigastric region; 

 the superior concave one is 

 pariially related with the small 

 curvature of the third com- 

 partment. The left extremity 

 in separated from the rumen 

 by a fissure, in which runs the 

 inferior artery of the reticu- 

 1 m The right forms a roimd 

 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 coinmunicates with 

 the left sac of the rumen, the 

 cesophagus, and third com- 

 partment. The communica- 

 tion with the two latter is by 

 the oesophageal canal, a con- 

 tinuation of ihe oesophagus, 

 which commences at the car- 

 diac oriiice, passes along the 

 roof of the retictdum, and 

 enters the third compartment 

 by a circular opening. Its 

 sides consist of two movable 

 lips, the (esophageal pillars, 

 which are continuous with the 

 muscular wall of the oesopha- 

 gus, and are attached by one 

 border to the superior 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 

 i6 a sort of valve, formed by 

 the attachment of the piUars to its walls 



Fio. 131. 

 Compartments of a Ruminant Stomach, laid open. A, 

 Kumen— a, a, a, a, Pillars ; 6, 6, Papillas ; c, (Esophageal 

 orifice. B, Eeticulum — a, a, Alveoli ; 6, CEsophageal 

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

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

 from large to small. X», Abomasum— a, a, Polds of 

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



The mucous membrane of thia 



2b 



