38 THE PAST CONDITION 



In this way to preserve unmistakable records of animal 

 and vegetable life. Whenever the sea-bottom, by some 

 of those undulations of the earth's crust that I have referred 

 to, becomes upheaved, 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 

 period. 



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 limestones are 

 able to convey anything like an accurate or complete 

 account of the animals which 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 hundreds 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 

 ami remove them. 



Almost all the hard parts of animals the bones and 

 so on are composed chiefly of phosphate of lime and 

 carbonate of lime. Some years ago, I had to make an 

 inquiry into the nature of some very curious fossils sent 

 to me from the North of Scotland. Fossils are usually 

 hard IMHIV structures that have become imbedded in the 

 way I have described, niid have gradually acquired the 

 nature :md solidity o f the body with which they are asso- 

 ! ; but in this case I had a series of holes in some 

 pieces of rock, and nothing else. Those holes, however, 



