368 COMPARATIVE SPLANCHNOLOGY. 



iorly the insertion of the oesophagus, and is also continuous anteriorly with 

 the second compartment. The anterior extremity is bounded by the second 

 and third compartments, and lies near the diaphragm ; the posterior occupies 

 the entrance of the pelvic cavity, where it contacts the urino-genital organs. 

 In the female, the uterus is prolonged over this surface. 



The superior surface is related with the intestines ; the inferior rests upon 

 the abdominal floor ; the left side, to which the spleen is united, is in contact 

 with, and attached by cellular tissue to the abdominal wall in the lumbar 

 region. The right side is related with the fourth compartment in the right 

 hypochondriac and lumbar regions, and is surrounded by convolutions of the 

 intestines. 



The interior of the rumen is incompletely divided into four sacs by fleshy 

 pillars. The principal ones are the anterior and posterior, which correspond 

 to the anterior and posterior fissures ; processes from these run transversely, 

 corresponding to constrictions on the outer surface ; thus anteriorly there are 

 formed the right and left sacs ; posteriorly the right and left conical sacs. 



The rumen, like the other compartments, consists of three coats ; an external 



Set. 



FIG. 130. 



Stomach of a Sheep seen from the left side the last three compart- 

 ments are laid open and reflected forwards, a', (Esophagus ; Ru., 

 Rumen; Ret., Keticulum ; Ps., Psalterium ; A., Abomasum ; Z>i/., 

 Duodenum. The cesophageal canal is seen traversing the lesser curva- 

 ture of the reticulum. 



serous, a continuation of the peritoneum, which envelops the entire organ, 

 excepting where it contacts the lumbar region ; the thick muscular middle 

 coat is an extension from the cesophageal fibres ; the internal mucous coat is 

 cuticular, papillated and covered by thick epithelium. The papillae are foliate 

 or leaf-like, conical, and fungiform, the first variety being by far the most 

 numerous. The rumen has two openings, both of which enter the anterior 

 extremity of the left sac : the superior, or cesophageal, which opening is pro- 

 longed over the small curvature of the second compartment by the cesophageal 

 canal, shortly to be described ; the inferior^ large and communicating with the. 

 reticulum, is circumscribed laterally and below by the free border of a kind 

 of valve, formed by the walls of the rumen, along with the cells of the second 

 compartment. 



The second compartment, or reticulum, the smallest of the four, is slightly 

 bent upon itself, and placed transversely between the posterior surface of the 

 diaphragm and the anterior extremity of the left sac of the rumen. The anterior 

 surface adheres to the centre of the diaphragm by cellular tissue ; the posterior 



