THE TEETH 29 



and is probably due to the displacement of a supernumerary dental germ 

 in the groove. Their exposed portion presents considerable variation 

 in shape. Usually they are somewhat tubercular, but occasionally one 

 is observed with a crown which resembles in shape that of a small 

 molar. 



Canine Teeth 



There are four of these, two in each jaw, and they are frequently 

 referred to as tusks or fangs. They are characteristic of the male, but 

 in rare and exceptional cases they are met with in the female. 



The tusks of the upper jaw are much more posteriorly placed than 

 are those of the lower. In the former the alveoli are situate immediately 

 in front of the projecting anterior extremity of the superior maxilla, 

 whilst those in the inferior maxilla are found almost immediately behind 

 the alveoli for the corner incisors. The outer surface of the exposed 

 part of the tusk is convex transversely, and presents a faint longitudinal 

 striation. This surface is separated from the inner by two well-defined 

 edges. The inner surface presents a small rounded elevation, and on 

 either side of this, and separating it from the edges, is a slight depression 

 or groove. The fang of the tusk is curved, and presents a large pulp 

 cavity, which, as in the case of the incisors, becomes filled up as the 

 animal advances in years. But the exposed portion presents no 

 infundibulum, and does not change its appearance except that it becomes 

 more yellowish in colour. That this is the only change is due to the 

 fact that the teeth, owing to the difference in position in the two jaws, 

 do not come mto apposition with one another. There is, therefore, no 

 friction, and in consequence no change in the teeth due to wear of their 

 exposed surfaces. The canine teeth are not replaceable. 



The Teeth as an Evidence of Age 

 Although the time of eruption of the teeth is subject to considerable 

 variation, depending upon the habits and uses of the animal, the nature 



