guished from all others,--I mean the skull. The differences
between a Gorilla's skull and a Man's are truly immense (Figure 16).
In the former, the face, formed largely by the massive jaw-bones,
predominates over the brain case, or cranium proper: in the latter, the
proportions of the two are reversed. In the Man, the occipital foramen,
through which passes the great nervous cord connecting the brain with
the nerves of the body, is placed just behind the centre of the base of
the skull, which thus becomes evenly balanced in the erect posture; in
the Gorilla, it lies in the posterior third of that base. In the Man,
the surface of the skull is comparatively smooth, and the supraciliary
ridges or brow prominences usually project but little--while, in the
Gorilla, vast crests are developed upon the skull, and the brow ridges
overhang, the cavernous orbits, like great penthouses.

Sections of the skulls, however, show that some of the apparent defects
of the Gorilla's cranium arise, in fact, not so much from deficiency of
brain case as from excessive development of the parts of the face.
The cranial cavity is not ill-shaped, and the forehead is not truly
flattened or very retreating, its really well-formed curve being simply
disguised by the mass of bone which is built up against it (Figure 16).

But the roofs of the orbits rise more obliquely into the cranial cavity,
thus diminishing the space for the lower part of the anterior lobes of
the brain, and the absolute capacity of the cranium is far less than
that of Man. So far as I am aware, no human cranium belonging to an
adult man has yet been observed with a less cubical capacity than
62 cubic inches, the smallest cranium observed in any race of men by
Morton, measuring 63 cubic inches; while, on the other hand, the most
capacious Gorilla skull yet measured has a content of not more than
34-1/2 cubic inches. Let us assume, for simplicity's sake, that the
lowest Man's skull has twice the capacity of that of the highest
Gorilla.* ([Footnote] *It has been affirmed that Hindoo crania sometimes
contain as little as 27 ounces of water, which would give a capacity of
about 46 cubic inches. The minimum capacity which I have assumed above,
however, is based upon the valuable tables published by Professor R.
Wagner in his "Vorstudien zu einer wissenschaftlichen Morphologie und
Physiologie des menschlichen Gehirns." As the result of the careful
weighing of more than 900 human brains,