PITHECANTHROPUS E RECTUS, ETC. 357 



and, as far as is profitable, a diminution of the alimentary 

 apparatus. Further, we may infer that a man, or an 

 anthropoid, with a small brain and a large masticatory 

 apparatus is an approach towards the primitive primate 

 stock that gave them birth. Judged on this standard, the 

 Bengawan and Neanderthal individuals may be set down 

 as distinct human approximations to the primate stock. 



6. OTHER MODIFICATIONS OF THE HUMAN FOSSIL SKULLS 

 ENTAILED BY A LARGE MASTICATORY APPARATUS. 



The prominent supra-orbital ridges of the fossil crania 

 form one of their most characteristic features. The thick- 

 ness of the skull over the glabellar (supra- nasal) part of 

 these ridges measures in the Bengawan, Neanderthal and 

 Spy crania from 24 to 30 m.m., the describers failing to 

 give us more exact figures. Australian crania of the cyno- 

 cephalic type show frequently an almost equal glabellar 

 thickness. In modern European skulls the measurement 

 seldom exceeds 20 m.m. In gorilla skulls the glabellar 

 part measures, in thickness, from 30 to 35 m.m.; in the chim- 

 panzee from 25 to 28 m.m.; in the orang from 16 to 20 m.m.; 

 and in the gibbon from 12 to 14 m.m. In fossil and most 

 cynocephalic Australian skulls, as well as in those of the 

 gorilla, chimpanzee and gibbon, the glabellar part of the 

 supra-orbital ridge is as prominent as the supra-ciliary parts. 

 In the orang and in the Tilbury skull the supra-ciliary parts 

 are separated by a glabellar hiatus ; and in modern skulls 

 the glabellar part is extremely variable, being often present 

 and prominent in men, and often absent in women. There 

 can be little doubt that the main end of this supra-orbital 

 bar is to strengthen the encasement of the face, and provide 

 a more extensive cranial basis for the large masticatory 

 apparatus ; hence its large size in anthropoid and fossil 

 human skulls. Its development may in some degree be 

 dependent also upon sexual elements, for it is commonly 

 larger in the male than in the female, in whom it frequently 

 begins to grow when the child-bearing period is past. The 

 prominence of the supra-orbital ridges is due, according to 



