REPORT ON THE HUMAN CRANIA. 
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Australian 26, another 44, another 55 mm. behind the bregma. There are two factors 
which influence the relation of this point to the bregma, viz., the inclination of the plane 
of the foramen magnum and the relative length of the longitudinal arc of the frontal bone. 
This line I shall call the perpendicular radius, and the extent of cranial cavity which 
lies anterior to it, and in relation to the cranial vault, will approximately correspond to 
the frontal lobes of the cerebrum. I have constructed Table XVIII. , in which is given the 
length of these different radii expressed in millimetres in the series of skulls which have 
been measured, and. to them I have also added for convenience of reference the basi- 
nasal and basi-alveolar diameters obtained in the previous measurements by the callipers. 
The new radial measurements are as follows : — basi-occipital from basion to occipital 
point ; basi-lambdoidal from basion to lambdoidal suture ; perpendicular from basion to 
cranial vault perpendicular to plane of foramen magnum ; basi-glabellar from basion to 
the most projecting part of the glabella ; whilst the basi-coronal from basion to coronal 
suture, corresponds with the basi-bregmatic diameter. 
From the perpendicular radius the distance was measured to both the most anterior 
and most posterior parts of the cranial cavity, and these measurements are also recorded 
in this Table. It will be seen that in the dolichocephalic Fuegian, Admiralty Islander, 
and Oahuan skulls, the extent of brain cavity behind the perpendicular radius exceeded that 
which was in front by several millimetres ; in the mesaticephalic Bush, New Zealander, 
and Chatham Islander, and in the brachycephalic Hawaian, on the other hand, a larger pro- 
portion of the cavity was in front of than behind the perpendicular radius. 
It would seem therefore as if in the formation of some dolichocephalic skulls, the 
growth takes place backwards, behind the plane indicated by the perpendicular radius, 
to a greater extent than in front of the same plane. This remark, however, must not 
be made too absolutely, for, owing to the plane of the foramen magnum not always 
possessing the same definite relation to the horizontal plane of the head, the perpendicular 
radius may, as already stated, be moved forwards and backwards. Thus in two of the 
three dolichocephalic Australian skulls measured in the above Table, where the plane of 
the foramen magnum sloped backwards, the frontal division of the cavity exceeded the 
occipital by a number of millimetres ; but in the dolichoplaty cephalic Gippsland skull, 
where the perpendicular radius reached the cranial vault much closer to the bregma, the 
anterior and posterior divisions of the cranial cavity were nearly equal. It will also be 
seen that, in accordance with the development of the cranial cavity behind the perpen- 
dicular radius, the basi-occipital and basi-lambdoidal radii attained considerable magnitude 
in the dolichocephali. and in the brachycephalic and mesaticephalic skulls the basi- 
glabellar radius preponderated over the basi-occipital. The tapeinocephalic character of 
both the Bush and Gippsland crania is well shown by the shortness of both the perpen- 
dicular and basi-bregmatic radii. 
Another relation to which my attention has been directed is the angle which a line 
(ZOOL. CHALL. EXP. — PART XXIX. — 1884.) Ff 16 
