150 THE ROYAL SOCIETY OF CANADA 



I have therefore merely chosen a few names representative of the 

 various schools of thought on this subject. 



Since the publication of the classical researches of Huxley' 

 and Turner^ on the cranio-facial axis, a fresh impetus to the com-' 

 parative study of the human skull has been furnished by the dis- 

 covery of the remains of the Java man-ape,^ the numerous additional 

 specimens or examples of crania of Neanderthal^ or Mousterian^ 

 man, and lastly the discovery of the fossil remains of Piltdown^ 

 man in 1912. The latter discovery has proved the main stimulus to 

 the production of this memoir for it impressed me with the value of 

 making a comparative investigation of the various cranial types of 

 fossil hominidae, and even carrying the evolutionary idea back to the 

 man-ape of Java {Pithecanthropus erectus) and the anthropoid apes. 

 Many of the results thus obtained were found to justify the extension 

 of the investigation along these channels. In carrying out this 

 research it was found that the most valuable information gained 

 from the evolutionary standpoint was secured by a study of the 

 following indices and cranial measurements, which will be considered 

 in their turn — 



1. The fronto-parietal index. 



2. The calvarial height. 



3. The bregmatic angle and the cranial curvatures. 



4. Other angular cranial measurements. 



I. The Fronto-parietal Index 



The post-frontal, or more accurately, the post-orbital con- 

 striction is a very marked feature of the skulls of the anthropoid 

 apes, when studied from above. It is also very prominently displayed 

 in the skull of the Java man-ape, as shown in Fig. 1 where it is indicated 

 by the line AB. In this skull its extent is actually 35% less than 

 that of the maximum parietal breadth, represented by the line DE. 

 This figure has been drawn to the scale of a glabella-inion length of 

 100 mm. In Fig. 1, a similar outline of the well known model of 

 the Neanderthal skull is shown, reduced to the same scale. On 

 comparing these two, it will be observed that the maximum parietal 

 breadth has increased only 9-5% whereas the minimum post-orbital 



^ Jour, of Anat. and Phys. Vol. I. 

 2 Op. cit. 



^ Archiv fur Anthrop, 1895. Jour. Anat. and Phys., 1895, and Smithsonian 

 Report, 1898. 



* Der Neanderthalschadel, Bonner Jahrbiicher, 1901. 



^Archives de Biologie. Tome VII. 



6 Quart. Jour. Geolog. Soc. London Vol. LXIX, 1913. 



