DENTITION AND DIEV. 131 
the central enamel is almost worn off. At twelve the corner teeth 
take on 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 corner 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. 1. 
A PORTION OF THE LOWER JAW OF OLD RLACK HAWK, 
(Aged twenty-three years and eight munths.: 
and as the animal increases in years, the upper corner tccth be- 
come indented or notched. The znelination of the teeth enables 
us to form some idea of the horse’s age. In a young horse, the 
tecth are upright (sce 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, on 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- 
tions of youth; for, as the animal advances in years, the tushes 
