62 2 THE POPULAR SCIENCE MONTHLY. 



dantly; where the reio deer occurs in the lower levels associated 

 with the mammoth, woolly rhinoceros, hyena, etc., it is not 

 abundant. 



It seems more reasonable to suppose that these tropical forms 

 were adapted to the cold climatal conditions in some way, as the 

 mammoth and woolly rhinoceros were, or that the conditions 

 were not as severe as the immense accumulations of ice would 

 lead us to imagine, for, as we have seen, if the precipitation is 

 great, the mean temperature need not necessarily be very low. 



Prof. James Geikie thinks that during the Glacial epoch there 

 were periods of high temperature, when the glaciers retreated and 

 tropical animals migrated into the glacial region. However this 

 may be, it is evident from what has been said that these tropical 

 animals, with the woolly rhinoceros and mammoth, were either 

 interglacial or preglacial or both. These data are important, as 

 they fix the age of the associated human remains. 



There is considerable diversity of opinion as to the value of 

 the evidence of man's existence prior to the Pleistocene or early 

 Quaternary such evidence as we have being open to criticism or 

 at least to the objection that it is not conclusive ; it is founded 

 principally upon roughly worked flints and flint chippings, per- 

 haps and perhaps not made by man, as their occurrence can, at 

 least to the satisfaction of some, be otherwise accounted for ; also 

 upon fossil bones of extinct mammals that bear markings sup- 

 posed to have been made by contemporaneous man. Such bones 

 have been found in both Pliocene and Miocene formations, and 

 their incisions difl^erently interpreted by difi^erent naturalists. 

 Qaite recently Prof. Cope has found in the Pliocene of southwest- 

 ern Oregon obsidian implements of human manufacture associ- 

 ated and interbedded with remains of fossil birds, but by what 

 agency they got there has not been determined. 



The argument has been advanced as to Miocene man that, as 

 all the mammalia of this period are extinct, it does not appear rea- 

 sonable that man alone should survive the causes that proved so 

 fatal to the rest of the mammalia. Against this it may be urged 

 that man's superior intelligence would enable him to overcome 

 adverse circumstances that would prove destructive to other 

 forms. In fact, this superior intelligence may have been a potent 

 factor in the destruction of the other forms. 



In 18G3 M. Desnoyes found in the gravel pit of Saint Prest, 

 near Chartres, a leg bone (tibia) of a rhinoceros. It bore marks 

 resembling those undoubtedly made by man on other more re- 

 cent bones. Reasoning by analogy, the marks on the Saint Prest 

 bone are also supposed to have been made by man. In the Vic- 

 toria cave, Yorkshire, there was found a human leg bone (fibula). 

 Both of these deposits have been considered by competent au- 



