166 THE ROYAL SOCIETY OF CANADA 



figures found by Biichner^ in aboriginal Australian and Tasmanian 

 skulls. From these varying distances one can readily appreciate step 

 by step the evolution of the frontal cranial arc from the lowest types 

 of both modern and fossil hominidae. In constructing Fig. 7, I was 

 fortunate enough to secure a modern European type of skull with 

 practically the same length of glabella-bregma chord (11-5 and 11-3 

 cm.) and the same maximum distance between the frontal cranial arc 

 and the chord (25 mm.) as those of the Piltdown cranium, but with a 

 bregmatic angle of 55° (as against 50°). It will be noticed in this figure 

 that if the Piltdown cranial arc were to be swung upwards by increasing 

 the size of the bregmatic angle to 55°, the area GaB' would almost 

 exactly coincide with the area GaB of the modern skull except in the 

 region of the superciliary ridges. That is to say, if the bregmatic 

 angle of the Piltdown skull had been a little greater the slope of the 

 forehead would have almost exactly corresponded to that of the 

 average modern European type. This is quite a remarkable fact 

 when considered in conjunction with the admittedly great antiquity 

 of Piltdown man, and shows evidently that the evolution of the 

 frontal cranial arc as such has remained practically stationary since 

 his time; the extra amount of uplifting necessary to produce the 

 modern orthognathous type of forehead being effected by increasing 

 the size of the bregmatic angle. It should of course be noted that the 

 description of this expansion has so far had reference entirely to the 

 mesial plane of the cranium, but it may be noted in passing that the 

 front view of the reconstructed Piltdown frontal bone^ is quite within 

 the range of variation of this bone in the modern European type of 

 skull, this statement applying with equal force to the configuration 

 imparted by the modeller to the supraorbital arches. It is unfortu- 

 nate that the forehead of the Piltdown cranium is mostly recon- 

 struction with the exception of portions near the right and left margins, 

 for it is certainly difficult to accept the view that a skull with an 

 amount of frontal development far above that of many modern races 

 could lay claim to the low type of jaw accredited to it. The writer 

 is therefore inclined to support the recent opinion of Miller^ who 

 states that the characters of the Piltdown jaw are such that it could 

 not have belonged to the skull but to a new species of anthropoid ape 

 named by him Pan vetus. It was particularly unfortunate that no 

 traces of the Piltdown superior maxillae were found, as their configura- 

 tion would have cleared up many difficult problems, especially those 



^ op. cit: 



2 op. cit., PI. XVIII. 2. 



' Smithsonian Institution, Washington, Nov., 1915. 



