45 



The marks of the lower jaw having vanished, we now turn to the 

 upper jaw, where marks are still visible. 



At 9 years the marks of the nippers in the upper jaw disappear and 

 an incision is found in the corner tooth. At 10 the mark in the middle 

 teeth of the upper jaw is "worn off and at 11 the mark has also left the 

 corner teeth. 



At 12 years the corner tooth of the upper jaw shows an incision of 

 increased size. At 13 the nippers and middle teeth of the lower jaw 

 have become perfectly rounded and the tusks are blunt. At 14 the 

 corner tooth of the lower jaw becomes rounded. 



At 15 the nippers in the upper jaw are rounded. At 16 the middle 

 teeth assume the same appearance. At 17 the corner teeth of the 

 upper jaw are also rounded. At 18 the nippers in the lower jaw are 

 triangular. At 19 the middle teeth in the lower jaw are tringular. At 

 20 the corner teeth of the lower jaw assume the same form. 



At 21 the nippers of the upper jaw have become triangular. At 22 

 the middle teeth of the tipper jaw have the triangular form. At 23 the 

 corner teeth in the upper jaw have the triangular shape. 



At 24 all the teeth begin to assume a reversed oval shape. 



The formation and the change of the horse's tooth is subject to ir- 

 regularities, resulting from the varieties of food, which they grind on 

 pasture and in the stable and they are also subject to the results of 

 habits, which the horse contracts, such as cribbing, biting the manger 

 etc. 



