CAUSES OF PRESERVATION. 167 



The period during which the study of the earth's interior has been 

 successfully pursued is too limited, and the facts collected are too few, to 

 enable us to come to any satisfactory conclusion on this subject ; and we 

 must content ourselves with the hope that those who follow us may 

 gradually discover the secret springs which have regulated, and will con- 

 tinue to regulate, the extinction of ancient, and the production of new, 

 species of the animal creation. 



The subject is one of the highest interest, and is well calculated to 

 elevate our ideas of the Almighty Being, who, as it were before our eyes, 

 yet in a way unperceived by us, is able to accomplish incessant changes 

 in the animal creation, by which countless individuals and species are 

 disappearing, and others are rising to supply their places. 



