DENTITION AND DIET. 



131 



the central enamel is almost worn off. At twelve the corner teeth 

 take oh the triangular form, and their central enamel is very con- 

 tracted, and a yellow mark is left. At thirteen the sides of the 

 front teeth thicken, and they begin to assume a triangular appear- 

 ance, and the whole incisors of the lower jaw complete the trian- 

 gular form at the age of seventeen. At eighteen the front teeth 

 are somewhat flattened from side to side ; the flattening goes on 

 in the middle and comer teeth, and is completed at the age of 

 iwenty-one, giving them the appearance of a reversed oval. As 

 regards the marks in the upper incisors, they disappear from the 

 front teeth in the course of the ninth year, from the middle in the 

 tenth, and from the corner or lateral ones in the eleventh year ; 



Fig. 11. 



A PORTION OF THE LOWER JAW OF OI.I> BLACK HAWK, 



(Aged twenty-three years and eight months.) 



and as the animal increases in years, the upper corner teeth be- 

 come indented or notched. The inclination of the teeth enables 

 us to form some idea of the horse's age. In a young horse, the 

 teeth are upright (see fig. 10); after the age of eight they gradu- 

 ally become horizontal, (see "Black Hawk's" mouth,) and the 

 upper teeth overlap the under ones, and thus wear off their outer 



edge. 



The Tushes, or Canine Teeth. — Between the ages of four 

 and six the tushes, which, in the male, are four in number, make 

 their appearance. In shape they are conical, with a sharp point, 

 and curved. On the inside there are two furrows, which com- 

 mence at the base and meet at the apex, leaving a triangular 

 eminence between them. The sharpness of the apex, the degree 

 of curvature, and the distinctness of the furrows are good crite- 

 rions of youth ; for, as the animal advances in years, the tushes 



