266 THE WORLD OP LIFE 



skull was more than three feet long), the woolly and other rhino- 

 ceroses, the sabre-toothed tigers, etc.; North America has lost the 

 megalonyx and the Ohio mastodon; from South America, the 

 glyptodonts, mylodons, the megalothere, and the macrauchenia 

 have been swept away; while Australia no longer possesses the 

 diprotodon and various gigantic species of kangaroos and wombats. 

 In the northern hemisphere this impoverishment of the fauna has 

 been very generally attributed to the effects of the glacial period, 

 but, although this may have been a partial cause, it can hardly be 

 the only one. The mammoth, for instance, certainly lived during 

 a considerable portion of the glacial epoch, and if it survived thus 

 far, why should it disappear at the close? Moreover, all the Eu- 

 ropean mastodons and the southern elephant {Elephas meridionalis) 

 died out before the incoming of glacial conditions; and the same 

 is true of all the extinct elephants and mastodons of Southern 

 Asia. Further, a large number of English geologists believe the 

 brick earths of the Thames valley, which contain remains of rhino- 

 ceroses and elephants in abundance, to be of post-glacial age. As 

 regards the southern hemisphere, it can hardly be contended that 

 glacial conditions prevailed there at the same time as in the north- 

 ern half of the world. 



" It is thus evident that, though a very great number of large 

 mammals were exterminated (perhaps partly by the aid of human 

 agency) at the close of the Pleistocene period, when the group had 

 attained its maximum development as regards the bodily size of its 

 members, yet other large forms had been steadily dying out in 

 previous epochs. And it would seem that there must be some 

 general, deep-seated cause affecting the life of a species with which 

 we are at present unacquainted. Indeed, as there is a term to the 

 life of an individual, what is more natural than that there should 

 also be one to the existence of a species. It still remains indeed, 

 to account for the fact that the larger Pleistocene mammals had 

 no successors in the greater part of the world, but perhaps, is in 

 some way connected with the advent of man." ^ 



It is sometimes thought that early man, with onlv the rudest 

 weapons, would be powerless against large and often well- 



1 A Geographical History of Mammals, R. Lydekker, B.A., F.R.S., V.P.G.S. 

 etc., 1896, p. 18. 



