168 THE GEOLOGICAL SUCCESSION 



CHAPTER X. 



ON THE GEOLOGICAL SUCCESSION OF PLANTS AND ANIMALS, 

 OR THEIR DISTRIBUTION IN TIME. 



In the preceding chapters we have endeavored to show 

 that the operations of organic law are the same in plants 

 and animals. In order to render the argument complete, 

 it is necessary to consider them in the order of their ap- 

 pearance on the earth's surface ; and for this purpose we 

 must examine their fossil remains and their position in the 

 rocks. The study of these remains constitutes the science 

 of Paleontology one of the most essential branches of 

 Botany and Zoology. 



By this science we are taught that the present arrange- 

 ments of land and water, and the forms of animal and vege- 

 table life on the earth's surface, are the result of a long 

 succession of antecedent changes of which the earth's crust 

 has preserved the memorial. The History of the Earth has 

 been written in its strata, which have been very properly 

 termed " the leaves of the stone book." But the language 

 left on these stony pages can only be interpreted by a care- 

 ful and accurate knowledge of the living creation, and of the 

 laws which now govern the distribution and development 

 of species. Natural History is the alphabet of geology. 

 The highest attainments in the natural sciences are re- 

 quired for these researches. 



The knowledge of Botany which is required to throw 

 light on fossil plants, must be both varied and extensive. It 

 is obvious that the Linnaean system is of no use in deter- 



