ORGANIC GEOLOGICAL DYNAMICS. 639 



peopled the world in the various stages of its pro- 

 gress, as geology teaches us. That they were, like 

 our own animal and vegetable contemporaries, pro- 

 foundly adapted to the condition in which they 

 were placed, we have ample reason to believe ; but 

 when we inquire whence they came into this our 

 world, geology is silent. The mystery of creation is 

 not within the range of her legitimate territory; she 

 says nothing, but she points upwards. 



Sect. 6. The Hypothesis of the regular Creation 

 and Extinction of Species. 



1. Creation of Species. We have already seen 

 how untenable, as a physiological doctrine, is the 

 principle of the transmutability and progressive 

 tendency of species ; and therefore, when we come 

 to apply to theoretical geology the principles of the 

 present chapter, this portion of the subject will 

 easily be disposed of. I hardly know whether I can 

 state that there is any other principle which has 

 been applied to the solution of the geological pro- 

 blem, and which, therefore, as a general truth, 

 ought to be considered here. Mr. Lyell, indeed, has 

 spoken 11 of an hypothesis that "the successive crea- 

 tion of species may constitute a regular part of the 

 economy of nature :" but he has nowhere, I think, 

 so described this process as to make it appear in 

 what department of science we are to place the 

 11 B. iii. c. xi. p. 234. 



