378 



COMPARATIVE SPLANCHNOLOGY. 



largest, and curve outwards and upwards ; the upper pass outwards and down- 

 wards. The tusks continue to grow during the life of the animal. 



The molars also vary in shape, gradually increasing from the first to the last, 

 which is large and strong ; they are intermediate between herbivorous and 

 carnivorous, and somewhat resemble the human teeth. The first, which is 

 small, and corresponds to the wolf-tooth of the horse, is a permanent or true 

 molar, the next three are the premolars, and the remaining three, true molars. 



The stomach is simple and somewhat capacious ; it consists, as in the horse, of 

 two divisions, cardiac and pyloric, the latter being the smaller, but the division 

 externally is marked by a much more distinct constriction. At the upper and 

 left portion of the cardiac half is a small diverticnlum or cul-de-sac. The 

 oesophagus is infundibuliform at its termination. The mucous membrane, for 



FIG. 140. 



Caecum ami colon of a Hog inflated, a, Ilpum ; b b, Caecum ; c c c, Colon 

 , Rectum. 



the most part villous in its structure, forms two folds which extend from the 

 cardiac towards the pyloric orifice, representing undeveloped ocsophageal pillars 

 and canal. 



In the general sense the intestines resemble those of the ruminant, but only 

 the posterior part of the colon lies between the folds of the mesentery. A 

 Peyers patch of enormous size occurs at the terminal portion of the small 

 intestine. The ccecum resembles that of the horse in having longitudinal 

 muscular bands, three in number, and transverse constrictions, and that 

 of the ruminant in its shape, and the direct continuity of its canal with 

 that of the colon ; the latter is coiled in a similar manner to that of the 

 ruminant, 



