OF ORGANIC NATURE. 43 



preserved and firmly imbedded in the limestone or 

 sandstone which is being thus formed. You may see 

 in the galleries of the Museum upstairs specimens of 

 limestones in which such fossil remains of existing 

 animals are imbedded. There are some specimens in 

 which turtle's eggs have been imbedded in calcareous 

 sand, and before the sun had hatched the young turtles, 

 they became covered over with calcareous mud, and 

 thus have been preserved and fossilized. 



Not only does this process of imbedding and fos- 

 silization occur with marine and other aquatic animals 

 and plants, but it affects those land animals and plants 

 which are drifted away to sea, or become buried in 

 bogs or morasses ; and the animals which have been 

 trodden down by their fellows and crushed in the mud 

 at the river's bank, as the herd have come to drink. 

 In any of these cases, the organisms may be crushed 

 or be mutilated, before or after putrefaction, in such a 

 manner that perhaps only a part will be left in the 

 form in which it reaches us. It is, indeed, a most re- 

 markable fact, that it is quite an exceptional case to 

 find a skeleton of any one of all the thousands of wild 

 land animals that we know are constantly being kill- 

 ed, or dying in the course of nature : they are preyed 

 on and devoured by other animals, or die in places 

 where their bodies are not afterwards protected by 

 mud. There are other animals existing in the sea, the 

 shells of which form exceedingly large deposits. You 

 are probably aware that before the attempt was made 

 to lay the Atlantic telegraphic cable, the Government 

 employed vessels in making a series of very careful ob- 

 servations and soundings of the bottom of the Atlantic ; 

 and although, as we must all regret, that up to the 



