[CAMERON-] THE HUMAN SKULL 155 



look in other directions for an expansion of the skull that is at all 

 commensurate with the high degree of cerebral evolution attained in 

 modern man. However, one of the most important facts shown so 

 far is, that the minimum post-orbital diameter, the maximum parietal 

 breadth, and the fronto-parietal index of the Piltdown skull are all 

 consistently within the range of variation of these in the skull of 

 nvodern white races. Another significant point illustrated in Figs. 1 

 and 2 is the progressive attempt to obliterate the post-orbital con- 

 striction which is definitely manifested during the evolution of the 

 human skull. 



Fig. 3. — The four lines represent antero-posterior cranial outlines in the mesial 

 plane, all drawn to scale on the same standard glabella-inion base line A B. 

 The line D E represents approximately the horizontal plane for all four 

 skulls. The lowest line represents the skull of the Java man-ape, the next 

 the Neanderthal cranium, the third a modern aboriginal Australian skull 

 and the fourth a modern European cranium. The third and fourth lines 

 did not absolutely coincide posteriorly at all points but the fluctuation of 

 the outlines was so slight that they have been represented there by the same 

 line in order to avoid confusion. Fig. 3 presents a suggestive mental pic- 

 ture of the remarkable strides made by the developing brain, and the con- 

 comitant expansion of the skull that has taken place in order to provide 

 accomodation for its growing cerebral contents. It may be noted that the 

 Neanderthal cranium, though degenerate, had at any rate begun well by 

 making remarkably uniform evolutionary progress when compared with 

 the Java Calvaria. The fig. shows that practically all the evolutionary 

 progress made by the modern Euiopean skull has been in the frontal region, 

 thus suggesting that the frontal lobes of the brain are amongst the last parts 

 of that organ to complete their phylogeny. 



