514 



CHORD ATA. 



The ox, on the other hand, starts from the bunodont 

 type found in the pig, with four principal crowns. These 

 do not unite transversely, but each independently becomes 

 crescentic, producing the selenodont or crescentic type of 

 molar. The crescents may unite longitudinally but not 

 transversely. 



The study of the teeth of these two types shows that 

 in this respect the ox is more specialised than the horse, 

 a conclusion which agrees with the comparative structure 

 of the stomach. The stomach of the horse is fairly simple ; 

 it is at most constricted into cardiac and pyloric portions, 

 whereas that of the ox has four distinct parts or chambers. 



Fig. 353. — Stomach of a Ruminant, Showing Internal 

 Structure. 



(Flower and Lyddeker.) 



a, CEsophagus ; b. Rumen (paunch) ; c. Reticulum (honeycomb) ; d, Psaherium 

 (many-plies); e, Abomasum (reed); f. Duodenum. 



The rumen (or paunch) is a large and capacious sac for 

 storage of food; the reticulum (or honeycomb bag) is a 

 small globose sac with reticulate walls : following this 

 is the psalterium (or many-plies) with folded walls, suc- 

 ceeded by the abomastim (or reed) which is the true 

 digestive stomach. The food is cropped and swallowed, 

 passing down to the paunch, in which it is stored. After 

 feeding, the animal retires to a secure retreat or at least | 

 comes to rest, and the food is passed by the reticulum 

 up the oesophagus into the mouth. Here the process of 



