A Period hi the Ilistonj of cnir Planet. 13 



fresh water, and of brackish water. Let it not bo objected, 

 that attempts have been made to separate salt and fresh water 

 formations in earUer strata. This has no doubt been done, but 

 without much foundation ; and the animals which ought almost 

 exclusively to determine such a separation — the fishes — do not 

 indicate such a difference until the tertiary period. Nay, my 

 inquiries into the fossil fishes would rather lead me to conclude 

 that the ancient seas were fresh water oceans ; and that it 

 was at a comparatively later period, and probably through 

 plutonic agency, that sea water acquired its quality of saltness. 

 Perhaps this agency may have exerted no inconsiderable in- 

 fluence upon the series of development of the different Faunas. 



The genera of molluscous and articulated animals, which at 

 the present day have representatives amongst living species, 

 become more and more numerous. The ammonites, those 

 voracious brachiopods, whose beautiful shells we meet with in 

 all strata until the period of which I am now speaking, vanish 

 as it were all at once ; and their place in relation to the other 

 lower animals seems to be supplied by the carnivorous piercers, 

 whose number is uncommonly increased, and of whose de- 

 structive appetites so many tertiary shells afford at the pre- 

 sent day the most decisive proof in the holes bored through 

 their masses. 



But what particularly characterises the tertiary beds is the 

 various remains of the bones of gigantic mammalia which are 

 found in them, and which Cuvier's creative hand made to arise 

 a second time out of the dust. 



These bones, the accidental finding of which gave occasion 

 to all the strange tales about giants of earlier ages, nay, as 

 linger has recently proved, to many of the fables about dragons 

 and other monsters, shew in the most evident manner how, 

 even in the mammalia, nature gradually elevated herself from 

 the ungainly, and, as it were, the grotesque, to the actually 

 beautiful, the symmetrical. The continent, to be sure, had 

 not yet assumed its present form ; arms of the sea stretched 

 far up into the land where there is now solid ground ; the chain 

 of the Alps had not yet arisen ; but still, those internal forma- 

 tions predominate which were deposited in large fresh-water 

 basins and extensive marshes. Only two of the many orders 



