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66 HUNTER ON THE TEETH.
The Enamel is continued farther down, and is thicker on the
anterior and back part of the Incisorcs than on their sides, and
is even a little thicker on the fore part than upon the back part
of the Tooth. If we view them laterally, either when intire, or

and to the entire skull. In the Gorilla, the transverse measurement of
the four incisor teeth is not greater than in the Chimpanzee ; they are
therefore proportionately smaller ; and in this respect, although still
very far removed, the Great Ape makes a nearer approach to human
dimensions. A further deviation from human type is seen in the
greater inequality of the incisors of the upper jaw, the central incisors
being considerably broader than the lateral. This inequality is greatest in
the Gorilla, but in both species it is a marked point of differentiation.
Each incisor has a well-developed prominent basal ridge on its posterior
surface ; and the outer angle of the crown of the lateral, instead of
being entire, as in Man, is rounded off. In the lower jaw these teeth
are equally characterised by their great size. As in Man, the lower
lateral are broader than the central ones ; but the former have the
external angles of the crowns rounded off. In both jaws the direction
of the incisive teeth departs from a vertical or nearly vertical position.
In the incisors of the Orangs we notice a still greater divergence from
human type in the superior breadth of the entire series, in the greater
size of the upper central teeth, and the greater amount of inequality
between them and the lateral. The central incisor of the upper jaw in
Pith. Satyrm and Pith. Mario is of unusual size and strength, being
double the width of the outer one, whdst its thickness is nearly equal
to its transverse measurement. From their constant use in overcoming
the resistance of hard and tough vegetable substances, they become
worn down ; and in the old Orang they present a broad abraded surface,
which extends obliquely backwards from the cutting edge to the
posterior margin of the base of the crown. The lateral incisors have
their external angles obliquely truncated ; in the lower jaw they exceed
in transverse measurement the dimensions of the central. In the
obliquity of their implantation in both jaws they exhibit the ordinary
Quadrumanous character. In the Gorilla and Great Orang, as in the
Quadrumana generally, a well-marked interval or diastema separates
the upper incisors from the canine.
The incisors are six in number in each jaw in the typical Carnivora.
In the Lion they form a transverse row; the outermost above is the
largest, and resembles a small canine ; the intermediate ones have broad
and thick crowns indented by a transverse cleft. These teeth are tin-
ployed in gnawing the gristly ends of bones, and scraping off the
attachments of periosteum and muscles. The crowns of the incisors in
the Hyamas form a similar transverse line ; the crown of the external
one above is laniariform; the crowns of the intermediate teeth are