432 



Proceedings of the Asiatic Society. 



[No. 4, 



external conditions. 



9. The tendency of all succes- 

 sive changes may be termed ter- 

 ripetal. The first population of 

 the globe was almost exclusively 

 pelagic. Land animals succeeded, 

 and increased most rapidly both 

 in numbers and in perfection of 

 organization. 



10. The higher and more per- 

 fect plants and animals are, so are 

 the conditions requisite for their 

 existence more complicated and 

 numerous. The more perfect ani- 

 mals could not exist without 

 the less perfect. And thus 

 a necessary consequence of the 

 progressive development of the 

 earth's surface, was a gradual 

 higher development of the or- 

 ganic world as a whole, as well as 

 of its subordinate divisions, and 

 while the organic world tended 

 more and more to the formation 

 of the existing higher types, the 

 latter tended to increase in a 

 more rapid ratio than the les3 

 perfect. Meanwhile many of the 

 less perfect either simply disap- 

 peared or were replaced by more 

 perfect compensating forms. 



11. There are also some special 

 cases in which the progression of 

 the organic world towards a 

 higher degree of development, 



cially characterized the close of the 

 carboniferous epoch and the com- 

 mencement of tertiary times. 



9. Simultaneous and parallel 

 with these changes was the di- 

 minution and sub-division of 

 watery areas and the formation 

 of continental, as distinguished 

 from insular divisions of the land 



10. The external conditions of 

 existence became more varied and 

 fitted for the existence of higher 

 organisms. 



