PRIMEVAL MAN 211 



lived even in such, geologically, near-by time as 

 any portion of the Pleistocene, we cannot be 

 sure of the exact time-parallelism of closely re- 

 lated faunas in different parts of the world, nor 

 can we, in many cases, tell whether certain 

 species were really contemporaneous or whether 

 they were successive. Of the general paleon- 

 tological facts, of the general aspects of the 

 various faunas in various parts of the world, 

 during some roughly indicated period of geo- 

 logic time, we may be reasonably sure. But 

 when we speak with more minuteness, we speak 

 doubtfully, and at any moment new discoveries 

 may unsettle theories by upsetting what we 

 have supposed to be facts. 



In considering what is in this chapter set forth 

 these conditions must be kept in mind. When 

 I speak of what I have myself seen or of the 

 tools, carvings, and skeletons dug from the 

 ground by competent observers, I speak of facts; 

 but as yet the explanations of these facts must 

 be accepted only as hypotheses, at least in part. 

 Just as the elephant, wild horse, and lion exist 

 in Africa to-day, and have disappeared from 

 Europe and the two Americas thousands or tens 

 of thousands of years ago, so it may well be 

 that they had died out in North America ages 

 before they had disappeared from the other end 



