THE SKULL AS A BASIS FOR RACE CLASSIFICATION. mil: 
‘but we know that great variations of cranium result from 
their premature closure, and in this way we may get a 
type of skull which is quite at variance with the common 
type of the race. We also know that pressure due to 
intra-cranial pathological causes may entirely prevent the 
-elosure of sutures and lead to extraordinary abnormal 
variations in cranial shape (Hydrocephalus). 
Thus, it seems to me that brain growth is the cause 
which directly determines cranial growth along those 
definite lines whose relative proportions provide the facts 
for cranial classification. 
The effect of heredity would be to perpetuate a form 
of cranium which corresponded with the evolution of the 
contained brain, subject, of course, to such additional modi- 
fication as depended upon further growth and evolution of 
the brain. On the other hand, intermarriage between 
people of different types of cranium would naturally result 
‘in modifications among the crania of their offspring, and 
‘thus we may have another reason for isolated cases of 
variation among the crania of primitive races. In elucida- 
tion of this argument I now direct attention to. certain 
observations taken by means of my segmenting callipers, 
and recorded in the Proceedings of the Royal Society of 
Edinburgh. 
These observations were conducted upon the skulls of 
‘certain primitive races showing well-marked types of 
Dolichocephaly and Brachycephaly, and the results are most 
interesting. 
Thus, an examination of transverse diameters showed that 
‘the crania were practically uever symmetrical on the two 
‘sides of the mesial plane, and, moreover, the asymmetry was 
always most pronounced in the parietal region, and least 
remarkable in the region of the cerebellum, while it pre- 
sented an intermediate condition in the frontal region. 
Now that is very much what might be expected from the 
relative importance of the corresponding parts of the brain, 
but the closure of the suture between the two parietal 
bones is, as a rule, much later than the disappearance of 
lines of union between the halves of the frontal bone or the 
‘segments of the occipital bone. 
