120 HOW TO BUY A HORSE. 



become triangular, and the central enamel is entirel}^ re- 

 moved from the second pair in the upper jaw. 



At seventeen years^ the sides of the triangle of the middle 

 nippers are all of the same length ; the central enamel has 

 entirely disappeared from the upper teeth. 



At eighteen years the sides of the triangle of the middle 

 nippers are longer at the sides of the teeth than in front. 



At nineteen years^ the middle nippers become flattened 

 from side to side, and long from front to rear. 



At twenty years^ the second pair assume the same form. 



At twenty-one years^ all of the teeth of the lower jaw 

 have become flattened from side to side, their greatest 

 diameter being exactly the reverse of what it was in youth. 



