DENTAL INDICATIONS OF AGE OF A HORSE I 9 



replaced. In six or eight days after birth, the 

 two central incisors make their appearance. These 

 are large in comparison to the size of the jaw, and 

 occupy its whole front, as represented in Plate iv, 

 fig i. In three weeks or a month the third tem- 

 porary molars will have made their appearance, 

 and within six weeks an additional incisor (middle) 

 on each side of the two first, both above and 

 below, will be visible, and soon after completed, 

 and the jaw will have assumed the form exhibited 

 in fig. 2. In from nine months to twelve months 

 the corner temporary incisors appear. The two 

 molars that the foal has at birth remain until the 

 animal is three years of age, at which time they 

 fall out of their sockets by the protrusion of the 

 second set, or permanent molars. But from this 

 time there is no use in consulting the grinders for 

 the age of the horse, as the best tests and easiest 

 come at are the incisors. The permanent molars 

 appear in the following order : the first permanent 

 (but the fourth by position in the jaw) at one year, 

 the fifth by position at two years ; the first and 

 second by position at three years ; the third and 

 sixth by position at four years. 



The incisor teeth are continually undergoing 

 some change, in consequence of the friction pro- 

 duced by the action of their rubbing against each 

 other. The anterior edge being considerably more 

 elevated and sharper than the posterior, the wear 

 first commences there, and in a short time it is 

 level with the posterior, then both wear together ; 

 the longitudinal cavity, or infundibulum, becomes 

 narrower, and afterwards triangular, and, finally, 

 at a certain period disappears, and is replaced by 

 the small end of the funnel next the root ; it is 



