oD DR DAVID HEPBURN ON 
Similarly, I have treated the glabello-occipital length by 
segmenting it in terms of perpendiculars dropped upon it 
from the bregma and the lambda, thereby approximately 
representing the amount of the brain lying under cover of 
the frontal, parietal, and supra-inial portion of the 
occipital bones respectively. In groups of skulls so widely 
apart as the dolichocephalic and brachycephalic, I found 
that practically the same percentage of the length was under 
cover of the parietal bones, but that in the latter there was 
dy more in front of the bregma, whereas in the former 
there was 1% more behind the lambda. From this I have 
argued that in the case of brachycephalic skulls growth at 
the coronal suture is in excess of, or more active than, growth 
at the lambdoidal suture, while the opposite condition prevails 
among dolichocephalic skulls. Further, such variation in 
relative rate of skull growth can only coincide with corre- 
sponding growth of brain. 
Among the members of @ civilised race, all kinds of skulls. 
may be found, although one type may predominate. Here 
we find more complex conditions, for although from its 
proportions a civilised skull may be classified with those of 
a savage race, yet we must take into account the greater 
average capacity of civilised skulls. We must also remember 
that proportions result from the rate of growth in different 
directions, and that this may be influenced by the early 
closure of sutures under conditions which we do not under- 
stand, although we might call them historical or reversionary. 
It seems to me that this is the simplest explanation of a 
dolichocephalic skull appearing among a brachycephalic or 
mesaticephalic race. 
Certainly it is a remarkable fact, that so far as primitive 
races are concerned, the skull which is most akin to that of 
lower animals—viz., the dolichocephalic type—should be so 
common, and that among such peoples it should also be 
associated with a facial condition similarly related to that of 
lower animals. On the other hand, a dolichocephalic skull 
appearing in a civilised race would almost certainly present 
a much greater capacity, and would not probably be associated 
with prognathism. 
The brachycephalic skull being that in which the pro- 
