EXCURSIONS OF AN EVOLUTIONIST 



vestigations of the Geological Survey of Portu- 

 gal, which have brought to light flint imple- 

 ments of undoubted human workmanship, in 

 great abundance in the Pliocene strata of that 

 country, buried under 1200 feet of superincum- 

 bent rock. These discoveries, set forth by M. 

 Ribeiro in 1871, are cited by Professor Whit- 

 ney as furnishing conclusive evidence of the 

 presence of man in Portugal during the Pliocene 

 period. In his admirable memoir on " The 

 Auriferous Gravels of the Sierra Nevada," Pro- 

 fessor Whitney has collected a great amount of 

 evidence which seems to prove that man existed 

 in California at an equally remote date. Now 

 it is perfectly clear that the human race must 

 have been in existence for a very long time be- 

 fore it could have become so widely dispersed 

 over the earth as to occupy countries so distant 

 from each other as California and Portugal. For 

 the first appearance of man on the earth we must, 

 therefore, go far back in the Pliocene period at 

 any rate ; and if we are to find traces of the 

 " missing link," or primordial stock of primates 

 from which man has been derived, we must 

 undoubtedly look for it in the Miocene. 



Of the three stages of the Tertiary period 

 here passed in review, we have seen that the 

 Eocene was characterized by the entire absence 

 of genera and species of mammals identical with 

 those now living ; in the Miocene there were 

 28 



