the
skull, or as much further back than that of the Gorilla, as that of the
Gorilla is further back than that of Man; while, as if to render patent
the futility of the attempt to base any broad classificatory distinction
on such a character, the same group of Platyrhine, or American monkeys,
to which the 'Mycetes' belongs, contains the 'Chrysothrix', whose
occipital foramen is situated far more forward than in any other ape,
and nearly approaches the position it holds in Man.

Again, the Orang's skull is as devoid of excessively developed
supraciliary prominences as a Man's, though some varieties exhibit great
crests elsewhere (See pp. 231, 232); and in some of the Cebine apes and
in the 'Chrysothrix', the cranium is as smooth and rounded as that of
Man himself.

What is true of these leading characteristics of the skull, holds good,
as may be imagined, of all minor features; so that for every constant
difference between the Gorilla's skull and the Man's, a similar constant
difference of the same order (that is to say, consisting in excess or
defect of the same quality) may be found between the Gorilla's skull
and that of some other ape. So that, for the skull, no less than for the
skeleton in general, the proposition holds good, that the differences
between Man and the Gorilla are of smaller value than those between the
Gorilla and some other Apes.

In connection with the skull, I may speak of the teeth--organs which
have a peculiar classificatory value, and whose resemblances and
differences of number, form, and succession, taken as a whole, are
usually regarded as more trustworthy indicators of affinity than any
others.

(FIGURE 17.--Lateral views, of the same length, of the upper jaws of
various Primates (Man, Gorilla, Cynocephalus, Cebus, Cheiromys). 'i',
incisors; 'c', canines' 'pm', premolars; 'm', 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 (Figure 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