10 ANIMALS OF THE PAST 



record must remain not only unread, but unseen. The 

 wonder is, not that we know so httle of the history of the 

 past, but that we have learned so much, for not only 

 is nature careless in keeping the records — preserving 

 them mostly in scattered fragments — but after they 

 have been laid away and sealed up in the rocks they 

 are subject to many accidents. Some specimens get 

 badly flattened by the weight of subsequently deposited 

 strata, others are cracked and twisted by the movements 

 of the rocks during periods of upheaval or subsidence, 

 and when at last they are brought to the surface, the 

 same sun and rain, snow and frost, from which they once 

 escaped, are ready to renew the attack and crumble 

 even the hard stone to fragments. Such, very briefly, 

 are some of the methods by which fossils may be formed, 

 such are some of the accidents by which they may be 

 destroyed; but this description must be taken as a 

 mere outline and as applying mainly to vertebrates, or 

 backboned animals, since it is with them that we shall 

 have to deal. It may, however, show why it is that 

 fossils are not more plentiful, why we have mere hints 

 of the existence of many animals, and why mjrriads of 

 creatures may have flourished and passed away without 

 so much as leaving a trace of their presence behind. 



REFERENCES 

 A very valuable and interesting article by Dr. Charles A. 

 White, entitled "The Relation of Biology to Geological Investi- 

 gation," will be found in the Report of the United States National 

 Museum for 1892. This comprises a series of essays on the 

 nature and scientific uses of fossil remains, their origin, rela- 

 tive chronological value and other questions pertaining to 

 them. The United States National Museum has published a 

 pamphlet, part K, Bulletin 39, containing directions for collect- 

 ing and preparing fossils, by Charles Schuchert; and another, 

 part B, Bulletin 39, collecting recent and fossil plants, by F. H. 

 Knowlton. 



