OF ORGANIC NATURE. 45 



the earth's crust that I have referred to, becomes np- 

 heaved, and sections or borings are made, or pits are 

 dug, then we become able to examine the contents and 

 constituents of these ancient sea-bottoms, and find out 

 what manner of animals lived at that pei'iod. 



Now it is a very important consideration in its 

 bearing on the completeness of the record, to inquire 

 how far the remains contained in these fossiliferous lime- 

 stones are able to convey anything like an accurate 

 or complete account of the animals Avhich were in 

 existence at the time of its formation. Upon that 

 point we can form a very clear judgment, and one in 

 which there is no possible room for any mistake. 

 There are of course a great number of animals — such 

 as jelly-fishes, and other animals — without any hard 

 parts, of which we cannot reasonably expect to find any 

 traces whatever : there is nothing of them to preserve. 

 Within a very short time, you will have noticed, after 

 they are removed from the water, they dry up to a 

 mere nothing; certainly they are not of a nature to 

 leave any very visible traces of their existence on such 

 bodies as chalk or mud. Then again, look at land 

 animals ; it is, as I have said, a very uncommon thing 

 to find a land animal entire after death. Insects and 

 other carnivorous animals very speedily pull them to 

 pieces, putrefaction takes place, and so, out of the hun- 

 dreds of thousands that are known to die every year, 

 it is the rarest thing in the world to see one imbedded 

 in such a way that its remains would be preserved for a 

 lengthened period. Not only is this the case, but even 

 when animal remains have been safely imbedded, certain 

 natural agents may wholly destroy and remove them. 



