412 



DIGESTIVE SYSTEM OF THE PIG 



The formula for the temporary teeth is: 



/ 3 1 4\ 



( Di - Dc - Dp - ) 

 V 3 1 4/ 



= 32 



The upper incisors are smaU ; they are separated from each other I^y spaces, 

 and from the canines by a larger interval. The first incisors are the largest, are 

 convergent, and have no distinct neck. The second are narrower and somewhat 

 smaller. The third (corner) incisors are much smaller, are flattened laterally, 

 and have three small eminences on the crown. 



The lower incisors are almost horizontal and are convergent and close to- 

 gether. The first and second are about equal in size, prismatic, and deeply im- 



FiG. 308. — Skull of Fig about a Year and a Half Old, Sculptured to Show the Embedded Parts of 



THE Teeth. 

 lis. Incisors; C, canines; Pl-4, premolars; MIS, molars. 



planted in the jaw. The labial surface is slightly convex, the lingual concave and 

 marked near its extremity by a ridge. The third incisor is much smaller and 

 has a short narrow crown and a distinct neck. 



The canine teeth or tusks of the male are greatly developed and project out 

 of the mouth. The upper canine of the boar may be about three or four inches 

 (ca. 8 to 10 cm.) long. The crown is conical and is curved somewhat backward 

 and outward; the embedded part is curved and has a large pulp cavity.^ 

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

 is prismatic and is curved l)ackward 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 l)ackwar(l. They have (with 



1 The canines of the pig are "permanent pulp" teeth and therefore capable of continued 

 growth, and are without roots in the strict sense. 



