THE INTRODUCTION OF NEW SPECIES. 13 



in geographical proximity. The question forces itself 

 upon every thinking mind, why are these things 

 so ? They could not be as they are had no law 

 regulated their creation and dispersion. The law 

 here enunciated not merely explains, but necessitates 

 the facts we see to exist, while the vast and long- 

 continued geological changes of the earth readily 

 account for the exceptions and apparent discrepan- 

 cies that here and there occur. The writer's object 

 in putting forward his views in the present imper- 

 fect manner is to submit them to the test of other 

 minds, and to be made aware of all the facts 

 supposed to be inconsistent with them. As his 

 hypothesis is one which claims acceptance solely 

 as explaining and connecting facts which exist in 

 nature, he expects facts alone to be brought to dis- 

 prove it, not a priori arguments against its pro- 

 bability. 



Geological Distribution of the Forms of Life. 



The phenomena of geological distribution are ex- 

 actly analogous to those of geography. Closely allied 

 species are found associated in the same beds, and 

 the change from species to species appears to have 

 been as gradual in time as in space. Geology, how- 

 ever, furnishes us with positive proof of the extinc- 

 tion and production of species, though it does not 

 inform us how either has taken place. The extinction 

 of species, however, offers but little difficulty, and 

 the modus operandi has been well illustrated bv Sir 



