THE TEETH. 47 
root and on its surface a groove, 
dividing the crown into three cusps, 
of which the centre one is the largest. 
iii, The premolars. There are four pairs 
borne by the maxilla. They increase 
in size from before backwards, the last 
—p 4—becoming specially modified. It 
is known as the sectorial or carnassial 
tooth. It forms a blade-like surface 
and has three cusps, the anterior and 
inner one being the smallest, the 
middle one the highest and most 
pointed, and the posterior having a 
sharp straight ridge. There are three 
roots, that of the inner cusp being 
distinct. 
ii. The canines are separated from the 
incisors by an interspace, they are two 
in number, borne by the maxilla. 
Each is slightly curved and pointed. 
iv. The molars are the two pairs of pos- 
terior teeth. The first is the largest. 
They have no deciduous predecessors. 
b. The teeth of the lower jaw. 
i. The incisors are six in number, as in 
the upper jaw. They differ from 
them in being slightly smaller, and 
in having the cusps more strongly 
marked. 
ii, The eanines of the lower jaw are 
