UNGULATA. 519 



plies." The vernacular and the first of these technical names 

 both refer to the fact that the inner lining of this cavity is 

 thrown into a number of longitudinal folds, which are so close 

 as to resemble the leaves of a book. The psalterium opens 

 by a wide aperture into the fourth and last cavity, the " abo- 

 masum" (a), both appearing to be divisions of the pyloric 



Fig. 199. Stomach of a Sheep, o Gullet; r Rumen or Paunch ; h Honeycomb-bag 

 or Reticulum ; p Manyplies or Psalterium; a Fourth Stomach or Abomasum. 



portion of the stomach. The mucous membrane of the abo- 

 masum is thrown into a few longitudinal folds, and it secretes 

 the true acid gastric juice. It terminates, of course, in the 

 commencement of the small intestine i.e., the duodenum. 

 The intestinal canal of Ruminants, as in most animals which 

 live exclusively upon a vegetable diet, is of great relative length. 

 The dentition of the Ruminants presents peculiarities al- 

 most as great and as distinctive as those to be derived from 

 the digestive system. In the typical Ruminants (e.g,, Oxen, 

 Sheep, Antelopes), there are no incisor teeth in the upper jaw, 

 their place being taken by a callous pad of hardened gum, 

 against which the lower incisors impinge (fig. 200). There 

 are also no upper canine teeth, and the only teeth in the 

 upper jaw are six molars on each side. In the front of the 

 lower jaw is a continuous and uninternipted series of eight 

 teeth, of which the central six are incisors, and the two outer 

 ones are regarded by Owen as being canines. Upon this 

 view, canine teeth are present in the lower jaw of the typical 

 Ruminants, and they are only remarkable for being placed in 

 the same series as the incisors, which they altogether resemble 

 in shape, size, and direction. Behind this continuous series of 

 eight teeth in the lower jaw there is a vacant space, which is 

 followed behind by six molars on each side. 



