OF ORGANIC NATURE. 47 



would be preposterous to imagine that the beasts had 

 nothing else but a lower jaw ! The probability is, as 

 Dr. Buckland showed, as the result of his observations 

 on dead dogs in the river Thames, that the lower jaw, 

 not being secured by very firm ligaments to the bones 

 of the head, and being a weighty affair, would easily 

 be knocked off, or might drop away from the body as 

 it floated in water in a state of decomposition. The 

 jaw would thus be deposited immediately, while the 

 rest of the body would float and drift away altogether, 

 ultimately reaching the sea, and perhaps becoming de- 

 stroyed. The jaw becomes covered up and preserved 

 in the river silt, and thus it comes that we have such 

 a curious circumstance as that of the lower jaws in 

 the Stonesfield slates. So that, you see, faulty as these 

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

 necessarily are as a record, the account of contempora- 

 neous vital phenomena presented by them is, by the 

 necessity of the case, infinitely more defective and frag- 

 mentary. 



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 century 

 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 dis- 

 covered. You have no more ground for doubting 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. 



