molars. A line is drawn through the first molar of Man, 'Gorilla',
'Cynocephalus', and 'Cebus', and the grinding surface of the second
molar is shown in each, its anterior and internal angle being just
above the 'm' of 'm2'.

Man is provided with two sets of teeth--milk teeth and permanent teeth.
The former consist of four incisors, or cutting teeth; two canines, or
eyeteeth; and four molars, or grinders, in each jaw--making twenty in
all. The latter (Fig. 17) comprise four incisors, two canines, four
small grinders, called premolars or false molars, and six large
grinders, or true molars, in each jaw--making thirty-two in all. The
internal incisors are larger than the external pair, in the upper jaw,
smaller than the external pair, in the lower jaw. The crowns of the
upper molars exhibit four cusps, or blunt-pointed elevations, and a
ridge crosses the crown obliquely, from the inner, anterior cusp to the
outer, posterior cusp (Fig. 17 m2). The anterior lower molars have
five cusps, three external and two internal. The premolars have two
cusps, one internal and one external, of which the outer is the higher.

In all these respects the dentition of the Gorilla may be described in
the same terms as that of Man; but in other matters it exhibits many
and important differences (Fig. 17).

Thus the teeth of man constitute a regular and even series--without any
break and without any marked projection of one tooth above the level of
the rest; a peculiarity which, as Cuvier long ago showed, is shared by
no other mammal save one--as different a creature from man as can well
be imagined--namely, the long extinct 'Anoplotherium'. The teeth of the
Gorilla, on the contrary, exhibit a break, or interval, termed the
'diastema', in both jaws: in front of the eye-tooth, or between it and