82 STUDIES IN LIFE AND SENSE. 



extent ; but the main lines of the biological argument are clear 

 enough to those who will consider, even casually, the evidence 

 already at hand. It is thus probable that the true elephants, which 

 belong to the Pliocene period, were ushered into existence, so to speak, 

 by forms that are less typical elephants mastodon and deinotherium 

 when judged by the standard of existent elephantine structure. 

 There are various species of mastodons known to geologists, which 

 exhibit a gradation in the matter of their teeth, and presumably in 

 other structural aspects as well, towards the ordinary elephant type. 

 As the mastodons precede the ordinary elephants in time, we shall 

 not be deducing an unwarrantable inference if we maintain that the 

 origin of the true elephants, both fossil and living forms, may safely 

 be regarded as arising from the mastodon stock. The elephants of 

 to-day are connected by links of obvious nature with the Pliocene 

 and Post-Pliocene forms ; and when the " ice age" cleared the earth 

 of the vast majority of the species, the progenitors of our living ele- 

 phants must have escaped destruction and have survived the cold, 

 possibly in the regions wherein they now exist, just as the mammoth, 

 in its turn, survived the rigours of the ice period, through the presence 

 of its woolly coating and its hardier constitution. There seems thus 

 to be no special difficulty, either of purely geological or of intellectual 

 nature, in conceiving that the elephants of to-day are simply survivals 

 of that elephantine host, whose existence was well-nigh terminated 

 by the ice age, and which left the mammoth, and the progenitors of 

 our living elephants, to replenish the earth after a catastrophe as 

 sweeping and fatal in its nature as any deluge. 



But if the origin of the modern and later elephants may thus be 

 accounted for, and if their geographical birthplace may be assumed 

 to exist within the confines of the Old World, a more fundamental 

 and anterior query may be put with reference to the origin of the 

 mastodon stock, which we have supposed, and with reason, is the 

 founder of the existing elephant races. From what stock, in other 

 words, did the mastodons themselves arise ? The chain of organic 

 causation, to be perfect and complete, cannot assume the mysterious 

 origin of the mastodon. That stock must, in its turn, have originated 

 in an ancestry less like the elephants than itself. It is not improbable 

 that the evolutionist of the future will seek and find the mastodon 

 ancestry in the deinotherium group, or in some nearly related forms. 

 For, as we have seen, the deinotherium exhibits a structure which 

 appears to relate the elephants to other and lower quadrupeds, such 

 as the sea-cows and their neighbours. 



If this supposition be permissible, then a further stage still awaits 

 our intellectual journey in the search after the origin of the elephant 

 races. In the Eocene rocks of North America, occur the fossil 

 remains of some extinct quadrupeds of which the Dinoceras is the 



