402 
THE ANTIQUITY OF MAN 
the frontal deserves our first consideration. It constitutes 
a large and important part of the brain. On its lower 
surface is seen the hollow impression formed by the roof 
of the orbit ; on the rounded lateral and upper surfaces 
which lie under the forehead can be detected at least three 
longitudinal elevations separated by irregular shallow 
depressions. The elevations indicate the upper, middle, 
IgO 
Fig. 145. — Diagram made from a brain cast of an Australian native, with a 
capacity of 1450 c.c. The divisions between the various lobes and convolu- 
tions of the brain have been emphasised. 
parts are indicated. 
The functional values of various 
and lower frontal convolutions. The lowest or third 
frontal convolution is very well marked ; it overlies the 
hollow caused by the roof of the orbit, and is separated 
from the temporal lobe by the stem or beginning of the 
fissure of Sylvius. Now the inferior frontal convolution 
is of particular importance for our present purpose ; it 
attains a large and special development in the human 
brain. In the anthropoid brain, on the other hand, it is 
not large, nor does it possess the human conformation. 
