56 NOTICES OF NEW BOOKS. 



ology are not less violated. Such extreme changes in the external 

 agents might well have destroyed the species, and they very probably 

 would have done so, but they could hardly modify them in any es- 

 sential point. 



" It seems therefore to me impossible that we should admit as an 

 explanation of the phsenomenon of successive faunas the passage of 

 species into one another. The limits of such transitions of species, 

 even supposing that the lapse of a vast period of time may have 

 given them a character of reality much greater than that which the 

 study of existing nature leads us to suppose, are still infinitely within 

 those differences which distinguish two successive faunas. 



" And lastly, one can least of all account by this theory for the 

 appearance of new types, to explain the introduction of which we 

 must necessarily, in the present state of science, recur to the idea of 

 distinct creations posterior to the first. 



" The theory o^ successive creations is the only one that remains, 

 and although it is, like the rest, opposed by very weighty objec- 

 tions, I am not aware of any good argument -directly impugning 

 it, and I believe that in the present condition of our knowledge it 

 is the only theory admissible, although I am bound to add that it 

 is by no means completely satisfactory, since it does not seem to 

 me to account sufficiently for all the facts, and perhaps it is at best 

 only provisionary. It explains well the differences which exist be- 

 tween successive faunas, but there are also resemblances between 

 these faunas for which it offers no explanation. 



" In order to illustrate the unsatisfactory nature of this theory, we 

 have only to compare two successive creations of the same epoch, 

 as for instance two faunas oF the cretaceous period. In such a com- 

 parison, no one could fail to be struck by the intimate relation that 

 exists among them, since most of the genera would be found the 

 same, while a large number of the species are so nearly allied that 

 they might easily be mistaken for one another. In other words, two 

 successive faunas often have the same physiognomical aspect ; and 

 in the case just mentioned, if we compare the turonian with the 

 alhian fossils (those of the upper chalk with the species from the 

 uppermost greensand), we shall readily find close resemblances. Is 

 it probable that the earlier fauna had been completely annihilated, 

 and then, by a new and independent act of creation, replaced by 

 another fauna altogether new and yet so much resembling it ? 

 Surely there must be something which has still escaped observation ; 

 but I must repeat, that the somewhat vague objections thus sug- 

 gested are in no way to be compared to those more definite ones 

 which militate against the other theories. 



" These facts also influence the manner in which we regard the 

 existing creation. Do all animals appear exactly as they issued from 

 the hands of the Creator, or have only a certain number of types 

 been introduced, whence the others were derived? It seems to me 

 difficult to admit that each one of those innumerable species, of the 

 accurate determination of which we are so often in doubt, was in all 

 its characters of detail a distinct and separate act of creation. 



