ON PEIMITIVE MAN : I. HIS TIMES AND HIS COMPANIONS. 239 



marsupials, we may point to the fact that the Eocene beds 

 in question are marine, and contain the remains of an 

 absolutely marine fauna. 



M. Arcelin has pointed out from personal observation 

 that the Thenay flints come from a bed of water-worn and 

 fractured flints, between which and themselves it is almost 

 impossible to find any difference ; whilst atmospheric, 

 chemical, and thermal agencies, which can be shown to have 

 been at work, are amply sufficient to account for various 

 appearances of fractm-e, supposed artificial chipping, and also 

 rif calcination. M. Arcelin has shown that alternations ot 

 heat and cold may bring about in a perfectly natural way the 

 splitting of the flints, and in places where forest fires were 

 kindled by liglitning, calcination would be produced. Many 

 travellers have also recorded the effects of the sun's heat 

 upon flints, after they have been refrigerated by the dew of 

 the early morning, and a similar result of change of 

 temperature has been observed to take place after sunset in 

 hot climates. Dr. Livingstone, the Marquis de Nadaillac, 

 M. Lepsius, and others have stated that they have both seen 

 and heard the flints splitting up into flakes under these 

 circumstances, and similar phenomena have been noticed by 

 M. Delvaux in Belgium. There is, hoAvever, one fact stated 

 by M. Rames, with regard to the flints found by him at 

 P'uy-Courny, which requires explanation, and that is that the 

 supposed implements are all made out of one particular 

 variety of flint, whilst there are other kinds present in the 

 same bed, bearing no such traces of fracture. This is a mat- 

 ter which ought to be considered, as it certainly would be 

 somewhat strange if only one variety of flint out of several in 

 the same place had been liable to accidental fracture, and M. 

 Raraes concludes from this that the selection must have been 

 intentionally made by an intelligent being ; but may it not be 

 that the fractured flints were derived from the denudation of 

 an older bed in which they originally occurred. 



Much stress has been laid on the presence of what has 

 been termed the bulb of percussion on a fhnt, as being a 

 clear proof of human workmanship, but it is not necessarily 

 so ; such a bulb only proves that the flake has been produced 

 by a single definite blow, but this might be given by a 

 natural shock, the dashing or faUing of one stone against 

 another as readily as by the hand of man. 



With regard also to chippings on one side only of a flint, 

 another supposed CAadence of artificial work, such might 



