168 THE ROYAL SOCIETY OF CANADA 



The examination of the Piltdown lambda-inion curvature and chord 

 displayed a similar result. The chord, I calculated to be about 56 mm. 

 and its maximum distance from the lambda-inion arc to be 7 mm., 

 both of which are well within the range of variation for the crania of 

 the higher races of modern mankind. Fig. 8 has been devised to 

 render this point more convincing, and at the same time represent it 

 in a graphic manner. A modern Canadian skull of the same glabella- 

 inion length as the Piltdown specimen, namely 190 mm., was chosen 

 in order to render the comparison more striking. On examining this 

 figure it is indeed almost impossible to determine which of the two 

 outlines represents the modern skull. The only essential difference 

 between the two is that the bregmatic angle in the modern cranium is 

 a little greater, namely fifty-five. Otherwise the configuration of the 

 two is wonderfully alike. Note that the frontal, parietal and occipital 

 arcs and chords very closely correspond to one another. 



Much valuable information regarding the evolution of the 

 frontal cranial arc was found to be gained from a comparative study 

 of it in the highest and lowest races of modern hominidse, as illustrated 

 in Fig. 9. I chose a Melanesian skull as it represented one of the 

 lowest types I have ever had the privilege of examining.^ Its breg- 

 matic angle was fifty-five, and I chose for comparison with it a Euro- 

 pean type of cranium possessing the same size of angle, and the same 

 length of glabella-bregma chord so as to render the effect more striking. 

 In the latter the maximum distance of the glabella-bregma arc from 

 the chord at approximately its centre was 24 mm. In the case of 

 the Melanesian skull the maximum distance was only 14 mm. which 

 was found to be at a point about two-thirds of the way from the 

 glabella to the bregma. These two curves make a rather effective 

 contrast in Fig. 9. It will be noted that the area included between 

 the Melanesian arc and chord is only about one-half of that included 

 between these in the European specimen. In other words the Melane- 

 sian frontal arc is only half "filled out," and it may be further observed 

 that the filling out process has so far mainly affected the upper half of 

 the frontal arc. Another significant fact demonstrated in Fig. 9, is 

 that the forcing outwards of the frontal arc by the phylogenetic frontal 

 lobes of the brain apparently begins at the bregmatic end and descends 

 in a sort of undulatory wave-like movement towards the glabellar end 

 which is last involved. I may state, however, that I found a Melane- 

 sian skull in which the main bulging was about the centre of the 

 frontal arc. Still the chief effect appears to commence from above; 

 for most of the skulls that I have examined certainly conveyed that 



1 op. cit. 



