than, the skulls of the lower mammals differ from those of Man.
Furthermore, the plane of the occipital foramen ('b c') forms a
somewhat smaller angle with the axis in these particular prognathous
skulls than in the orthognathous; and the like may be slightly true of
the perforated plate of the ethmoid--though this point is not so
clear. But it is singular to remark that, in another respect, the
prognathous skulls are less ape-like than the orthognathous, the
cerebral cavity projecting decidedly more beyond the anterior end of the
axis in the prognathous, than in the orthognathous, skulls.

It will be observed that these diagrams reveal an immense range of
variation in the capacity and relative proportion to the cranial axis,
of the different regions of the cavity which contains the brain, in the
different skulls. Nor is the difference in the extent to which the
cerebral overlaps the cerebellar cavity less singular. A round skull
(Fig. 29, 'Const'.) may have a greater posterior cerebral projection
than a long one (Fig. 29, 'Negro').

Until human crania have been largely worked out in a manner similar to
that here suggested--until it shall be an opprobrium to an ethnological
collection to possess a single skull which is not bisected
longitudinally--until the angles and measurements here mentioned,
together with a number of others of which I cannot speak in this place,
are determined, and tabulated with reference to the basicranial axis as
unity, for large numbers of skulls of the different races of Mankind, I
do not think we shall have any very safe basis for that ethnological
craniology which aspires to give the anatomical characters of the crania
of the different Races of Mankind.

At present, I believe that the general outlines of what may be safely