ON AGE AND APPEARANCE. 69 



by the presence or disappearance of the temporary teetb ; 

 tmd from five to eight by the disappearance of the mark, 

 which is commonly supposed to be tilled up, but in fact 

 disappears by the borders of the cavity being worn down. 

 It takes about three years to wear the teeth down to the 

 bottom of these cavities ; thus, the anterior or front teeth, 

 being first formed, are first to lose their mark; the middle 

 teeth following the next, and the corner teeth the succeed- 

 ing year. The French distinguish the incisor teeth by call- 

 ing the anterior ones the nippers, the corner teeth the cor- 

 ners, and those between them the dividers; which terms will 

 serve to distinguish them in this place. When the incisors 

 first appear, the anterior border of the cavity is somewhat 

 higher than the posterior internal border; but in the course 

 of a year it is worn down level. 



For many years it has been customary to judge the age of 

 the horse by marks in the teeth, but at eight years old the 

 horse loses those marks, and is said to be aged ; and after 

 this time it was considered to be impossible to ascertain 

 the age. There are, however, other means which will en- 

 able us pretty generally to judge of the age, if not with cer- 

 tainty, at any rate approaching to it. If we take an inci- 

 sor tooth and make three or four transverse sections of it, 

 we shall find that each surface is of a different shape. The 

 tooth becomes gradually less from side to side and more 

 from front to rear; at a certain depth it becomes triangular; 

 and, lower still, the oval appears almost reversed, the di- 

 ameter being less from side to side than from front to rear. 

 Each of these several portions of the tooth becomes, in the 

 course of time, its face, the shape of which therefore en- 

 ables us to approximate to the age. This is still more as- 

 sisted, up to a certain age, by the fact that the enamel that 

 forms the side of the infundibulum dips deeper into the 



