imian series.

It is the large proportional size of the facial bones and the great
projection of the jaws which confers upon the Gorilla's skull its small
facial angle and brutal character.

[Illustration: FIG. 16.--Sections of the skulls of Man and various Apes,
drawn so as to give the cerebral cavity the same length in each case,
thereby displaying the varying proportions of the facial bones. The line
'b' indicates the plane of the tentorium, which separates the cerebrum
from the cerebellum; 'd', the axis of the occipital outlet of the skull.
The extent of cerebral cavity behind 'c', which is a perpendicular
erected on 'b' at the point where the tentorium is attached posteriorly,
indicates the degree to which the cerebrum overlaps the cerebellum--the
space occupied by which is roughly indicated by the dark shading. In
comparing these diagrams, it must be recollected, that figures on so
small a scale as these simply exemplify the statements in the text, the
proof of which is to be found in the objects themselves.]

But if we consider the proportional size of the facial bones to the
skull proper only, the little 'Chrysothrix' (Fig. 16) differs very
widely from the Gorilla, and, in the same way, as Man does; while the
Baboons ('Cynocephalus', Fig. 16) exaggerate the gross proportions of
the muzzle of the great Anthropoid, so that its visage looks mild and
human by comparison with theirs. The difference between the Gorilla and
the Baboon is even greater than it appears at first sight; for the great
facial mass of the former is largely due to a downward development of
the jaws; an essentially human character, superadded upon that almost
purely forward, essentially brutal, development of the same parts which
characterizes the Baboon, and yet more remarkably distinguishes the
Lemur.

Similarly, the occipital foramen of 'Mycetes' (Fig. 16), and still
more of the Lemurs, is situated completely in the posterior face of 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 devo