FORE-GUT OF VERTEBRATA. 



559 



fuses with the stomach, of which it forms two divisions. The first 

 has the character of an enlarged fundus, and is known as the rumen 

 or paunch (Fig. 315, I) ; it functions essentially as an organ for the 

 reception of the large quantity of food that is ingested. Just below 

 the cardia it is connected with the second division, the reticulum 

 (II), which is succeeded by the psalterium (omasus) ; this third 

 portion is wanting in the Tragulidas and Tylopoda. The last 

 portion, which is formed from the pyloric part, is attached to this ; 

 it forms the abomasus, in 

 the mucous membrane of 

 which the rennet glands 

 are placed. A groove 

 (oesophageal groove) which 

 leads from the oesophagus 

 into the reticulum, and is 

 shut off by a valvular pro- 

 cess (Fig. 315, B s) from the 

 first two divisions of the 

 stomach, represents that 

 portion of the oesophagus 

 which has entered into the 

 formation of the stomach, 

 andformedthe first twopor- 

 tions of that organ by bul- 

 ging out on one side. Thanks 

 to its presence the food that 

 has passed from the reti- 

 culum into the oesophagus, 



and from thence into the mouth, can be directly returned, after it has 

 been sufficiently masticated, into the psalterium and abomasus, 

 while, when the groove is open, the fodder passes easily into the 

 paunch and reticulum. The influence of the food in determining 

 the size of the various portions may be seen from the differences 

 between the paunch and the abomasus at different periods of life. 

 The abomasus is relatively large in the calf, while later on the 

 paunch may be as much as ten times larger than the abomasus, 

 and even more than that. 



Fig. 315. Stomach of an Antelope. A From 

 in front. B Opened from behind, oe (Esopha- 

 gus. /Rumen. //Reticulum. ///Psalterium. 

 IV Abomasus. p Pylorus. s (Esophageal 

 groove. 



Mid-gut. 

 § 419. 



The mid-gut (small intestine) which is generally separated from 

 the stomach by a circular fold, the pyloric valve, is characterised at 

 its commencement by having glandular organs (liver and pancreas) 

 connected with it. With regard to length it is the most variable 

 portion of the enteric tube. It is straight in the Gyclostomata, 

 some Teleostei, and in Chimsera. In the last it is distinguished by 



