480 



DIGESTIVE SYSTEM OF THE PIG 



cavity. The lower canine may reach a length of eight inches or more (ca. 20 cm.) ; 

 the CTOvm is prismatic and is curved backward and outward in front of the upper 

 one, so that the friction between the two keeps a sharp edge on the lower tooth. 

 In the sow they are much smaller.^ 



The cheek teeth increase in size from before backward. They have (with 

 certain exceptions noted below) complex tuberculate crowns; the term bunodont 

 is applied to this condition, as distinguished from the lophodont and selenodont 

 structure in horses and cattle, in which there are prominent ridges of enamel. 



Fig, 415. — Superficial Glands of Head of Pig. 

 a, Parotid gland; a', a", cervical and mandibular angles of a; b, c, ventral and dorsal buccal glands; d, labial 

 glands; e, masseter muscle; /, /', lymph glands; g, dotted line indicating outline of mandibular gland, which is con- 

 cealed. (Ellenberger-Baum, Anat. d. Haustiere.) 



They are short-crowned teeth with a distinct neck and round, pointed roots. The 

 first tooth in each jaw is small, simple, and appears only once; in the lower jaw it is 

 near the canine; in the upper, near the second cheek tooth.^ The next two teeth 

 are larger, laterally compressed, and sectorial. The fourth tooth below is larger, 

 but otherwise like the preceding ones, while the upper one is much wider and is 

 tuberculate. The first premolar has two roots, the others three or four. The 

 molars have four roots, but the anterior pair may be largely fused. 



^ The canines of the pig are ' ' permanent pulp ' ' teeth and therefore capable of continued 

 growth, and are without roots in the strict sense. The convex surface is covered with enamel, the 

 concave with cement. 



^ It is often absent in the lower iaw. 



