224 MANUAL OF JIODERN FARRIERY. 



but the sides of the triangles are all of one length. (See 

 plate V. fig. 6.) 



At eighteen years, the lateral portions of the triangle 

 lengthen in succession. First the nippers, then the dividers, 

 and afterwards the corner teeth. 



At nineteen, the angles begin to wear off, the central 

 teeth are again oval, but in a reverse direction, that is, 

 from forward, inward, and the lower nippers are flattened 

 from one side to the other. 



This triangular form is not very much developed in the 

 beginning, the edges being slightly rounded, and the three 

 sides are very nearly equal in length ; . afterwards, the 

 lateral portions grow longer, whilst the anterior or outer 

 side appears to diminish, the extremities become angular ; 

 and this lengthening in a short time is so great, that at 

 from nineteen to twenty years of age the incisors have in 

 reality become flattened from one side to the other. This 

 flattening proceeds in succession from the nippers to the 

 dividers, and from them to the corner teeth, in such a way 

 as to enable us to distinguish the age of the horse up to 

 twenty-two to twenty-three years. 



At twenty, the dividers are of the same shape, and at 

 twenty-one, the whole teeth have acquired this form. 



After this period the incisors do not exhibit any par- 

 ticular characters whereby to guide us in determining the 

 age of a horse. They gradually become more flattened, 

 converging towards each other, and touching merely by 

 their lateral and anterior edge. Gradually they become 

 dried, and the gums whitened, the tables of the teetli 

 assume a greyish cast, the incisors in their whole extent 

 are frequently incrusted at their base by a thick coating of 

 ti'rtar. The jaw-bones also become narrow. 



In consequence of the continual growing up of the teeth 



