OF ORGANIC NATURE. 47 



layers of stone in the earth's crust are, defective as 

 they necessarily are as a record, the account of con- 

 temporaneous vital phenomena presented by them is, by 

 the necessity of the case, infinitely more defective and 

 fragmentary. 



It was necessary that I should put all this very 

 strongly before you, because, otherwise, you might 

 have been led to think differently of the completeness 

 of our knowledge by the next facts I shall state to you. 



The researches of the last three-quarters of a cen- 

 tury have, in truth, revealed a wonderful richness of 

 organic life in those rocks. Certainly not fewer than 

 thirty or forty thousand different species of fossils have 

 been discovered. You have no more ground for doubt- 

 ing that these creatures really lived and died at or 

 near the places in which we find them than you have 

 for like scepticism about a shell on the sea-shore. 

 The evidence is as good in the one case as in the 

 other. 



Our next business is to look at the general character 

 of these fossil remains, and it is a subject which will be 

 requisite to consider carefully ; and the first point for 

 us is to examine how much the extinct Flora and Fauna 

 as a whole — disregarding altogether the succession of 

 their constituents, of which I shall speak afterwards — 

 differ from the Flora and Fauna of the present day ; — 

 how far they differ in what we do know about them, 

 leaving altogether out of consideration speculations 

 based on what we do not know. 



I strongly imagine that if it were not for the pe- 

 culiar appearance that fossilized animals have, that 

 any of you might readily walk through a museum 



