DENTAL INDICATIONS OF THE AGE OF A HORSE. 229 
socket, are at first oval and then rounded, and jf a 
triangular form towards the base of the root, with the 
extremity flattened from side to side. This variation is 
much more remarkable in the nippers and dividers than in 
the corner teeth, which is rendered more obvious by making 
several sections of an incisor tooth at somewhat about a 
quarter of an inch apart. We have given five transverse 
sections of the tooth of a young horse to exhibit this : plate 
v. figs. 13, 14, 15, 16, and 17, have the funnel, and the 
sections, 16 and 17, show the septum of the root of the 
tooth. 
The incisors of the upper jaw are stronger, broader, 
and more developed than those of the lower ; consequently 
the outer edge of the lower corner teeth rest against the 
centre of the upper corners, and wears them in such a 
manner as to produce in some jaws a triangular nick, which 
leads in a certain degree to the determination of the age of 
a horse. This nick never appears until the horse has 
attained its seventh year. It becomes obliterated in time, 
but sooner in proportion as the jaw assumes a horizontal 
direction. 
We have given representations of six teeth, showing the 
exterior of the incisor teeth, together with their internal 
organization. 
The tooth of a foal viewed from its posterior or inner 
surface. Plate v. fig. 8 , a , the mouth of the cavity of 
funnel of the table. 
Another foal's tooth, viewed anteriorly, fig. 7 : a , exhibits 
the body of the tooth ; b , the neck ; and c , the root. 
The tooth of a very young foal, in which the casing 
or outer enamel is cut through its whole length, and 
exhibiting the central enamel, fig. 10 , a. 
The molars, or grinding teeth of Old Billy, mentioned at 
