PITHECANTHROPUS ERECTUS, ETC. 369 



must have lived in these early times are known to us by 

 only four specimens complete enough to permit of their 

 reconstruction. But, taking these as samples of their race, 

 we can say with some assurance that man has not changed 

 much since the Tertiary period of the earth's history closed. 

 The majority of men were distinctly and considerably 

 smaller-brained than the great majority of the men that 

 now people the earth's surface. Their faces, jaws, teeth 

 and muscular ridges were more pronounced. Since 

 Tertiary times the human structural progress has lain in 

 an increase of brain, and a diminution in the masticatory 

 and alimentary systems. In these features we may suppose 

 that early Quaternary man approached the primate ancestors 

 of the race ; in these features he certainly comes nearer the 

 present simian type. But, for the purpose of giving us a 

 clue to the human line of descent, the fossil remains at 

 present known assist us not one single jot. Their con- 

 figuration is quite conformable to the theory of a common 

 descent; they bear out the truth of that theory. They also 

 show us that man since the Tertiary period has changed 

 structurally very little. There is nothing remarkable in 

 this, for allied primate forms (Paleopitkecus sivalenses x and 

 Dryopitkectis 2 ) demonstrate to us that, since the Miocene 

 period, the anthropoid type has changed but slightly. We 

 need not then be surprised at being obliged to seek deep 

 within the Tertiary formations the evidences of human 

 descent. 



Arthur Keith. 



1 Lydekker, "Further Notices of Siwalik Mammalia," Records of the 

 Geological Survey of India, vol. xii., 1879, p. 7,$. 



2 Gaudry, Mem. Soc. Geol. France, vol. i. 



