332 
of the cranium measured accurately (with water) the capacity of the 
whole cranium can be calculated with pretty great certainty at about 
900 em*. by comparison with that of the small gibbon species. That is: 
with equal body size (weight), which may be estimated by the femur, 
double the capacity of the large Anthropoids, and more than two thirds 
of the cranial capacity of Modern Man (male Australian). The platy- 
cephaly, even of Pithecanthropus, which is much more considerable 
than that of the Neandertal Man, cannot be explained sufficiently as 
a primitive i.e. merely inherited character. With such a cranial 
capacity the platycephaly would have to be much less pronounced, if it 
were not adaptational. The form of the cranium of Pithecanthropus 
determined by about the same mechanical factors as in the small 
gibbon species, must also have gone together with an almost perfectly 
gibbon-like facial skull. Consequently the Ape Man carried his head 
in almost the same overhanging attitude as the small gibbon species, 
though the femur shows his completely ereet posture and gait. It 
may, therefore, be assumed that the nuchal muscles were exceedingly 
powerful, and the stress of the epicranial muscle apparatus very great, 
because in uniform skulls the areas increase only by squares, the 
weights — hence the muscular forces proportional to them -— by 
third powers. Therefore the very strong flattening of the parietal 
region and the development of the torus supraorbitalis which is 
about the same as in the smal! gibbon species. The rooflike shape 
(scaphoeephaly), which in Pithecanthropus is confined to the frontal 
bone, as in Homo rhodesiensis, and likewise the scaphocephaly which 
extends further as far as the parietal bones (lophus of Srrer) of 
Australians, Tasmanians, Eskimos and others, may be accounted for 
by the strain exerted as far as the median line on the periosteum 
by the anterior part of the temporal muscles, which part, active in 
biting. mastication, is then particularly powerful. This strain increases 
towards above, because the opposed strains of the two muscles meet 
in the median line. The mechanical efficiency of the roof shape lies 
in inerease of resistance of the cranial vault against the violence of 
the temporal muscles. 
The brain quantity, which is much too great for an Anthropoid of 
equal bodily size (weight), proves here certainly higher brain-organiza- 
tion. Judging by this relative quantity and the configuration of the 
cerebral convolutions of the frontal lobe, clearly impressed on the 
interior surface of the skull-cap, Pitheeanthropus presented a closer 
resemblance to Man than to the Anthropoids. Nevertheless the cranial 
shape. is almost absolutely ape-like; a proof that really even this form 
was determined partially by ana/ogous mechanical factors. 
