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94 HUNTER ON THE TEETH.

distance on the inside of the Tooth, slanting inwards. In this
Jaw these two Grinders are inclined outwards, and a little
forwards ; they project a little over the corresponding Teeth of

lower Quadrumana, in whom the grinding cusps rise from the surface of
the tooth distinct and unconnected. The third upper molar in Tr. niger
is the smallest of the series, in consequence of the minor development
of the two posterior cusps ; also, the oblique connecting ridge between
the antero-internal and postero-external cusp is either absent or feebly
developed. In the Gorilla, the last upper molar differs from the same-
tooth both in the Chimpanzee and in Man, in its greater size, being
equal to the second except at the posterior part, which is slightly
narrower, and in having both the posterior cusps, but especially the
inner one, much more distinctly marked. The connecting ridge between
the anterior internal and outer hind cusp is also present, but it is more
transverse than the same ridge in the other molars. Each upper molar
in both species of Troglodytes is implanted, as in Man, by one internal
and two external fangs. These have not been observed connate in any
of the Anthropoid Ape3. In the lower jaw, the three molar teeth of the
Gorilla are equal in size ; in the Chimpanzee they are nearly equal, the
first being only slightly larger than the last. In both species, the four
principal cusps, and especially the two inner ones, are more pointed and
prolonged than in Man ; but the fifth posterior cusp is proportionably
smaller. The fifth cusp is present in the second tooth ; it is usually
absent in the second molar of Man. The crucial depression which
separates the cusps is much less distinctly marked, and does not divide
the ridge connecting the anterior pair, as in the human lower molar-
Owing to the great development of the fifth posterior cusp, the crown of
the last molar is of longer antero-posterior measurement. The implan-
tation of these teeth resembles that in the human subject, except in the
fact that the two roots of the second and third are never found connate
in the Gorilla and Chimpanzee. The true molars in the Orangs
(Pithecus) differ from the true molars of the Chimpanzees in their
smaller relative size as compared with the premolars. Like the molar
series in Troglodytes, they form a straight line in both jaws ; and they
have a similar implantation, by three roots in the upper and two in the
lower jaw. In the superior series, the first and second teeth are
furnished with four cusps ; but they are less developed, and the depres-
sions between them are shallower ; the connecting ridge between the
antero-internal and the postero-external tubercles is either absent, or
but very feebly developed, so that, as before stated, the sigmoid character
of the elevated surface is not marked, as in Troglodytes ; the whole
grinding surface is flatter, and minutely wrinkled. In the lower jaw,
the first and second molars have three cusps along the outer side, and
two on the inner. The last tooth of the series has two external cusps