222 [September 



almost every little oceanic island has its peculiar species of insects, if 

 we accept Prof. Agassiz's theory we shall be compelled to believe, that 

 there must have been many hundred or even thousand distinct Crea- 

 tions within the present geological era. It may possibly have been so : 

 but views like these certainly do not harmonize with such demonstrable 

 entomological facts, as the existence of identical indigenous species in 

 faunas separated by a wide expanse of ocean, and they seem scarcely 

 consistent with the grandeur and simplicity of Nature. 



If, rejecting the Creative theory, we assume the Derivative Origin of 

 Species, how simple and intelligible become the great fticts of the geo- 

 graphical distribution of species ! How easily we can explain the ex- 

 istence of what are known as representative or analogous species, and 

 the occasional existence of identical specie'^, with all the intermediate 

 grades between the two categories, in distinct entomological provinces 

 separated by insurmountable physical barriers, such as are North Ame- 

 rica and Europe ! What Loew remarks of Diptera is, so fiir as my 

 personal knowledge of the entomological faunae of England and Illinois 

 extends, equally true of the other Orders of Insects. " The European 

 and the xVmerican dipterous faunas," says he, "always appear to me 

 like two branches of the same stock, each having had a development 

 of its own, very similar however to the development of the other. But 

 if there really was such a common stock for both, it is to be sought 

 among the Diptera of a former geological period, and if the European 

 and the North American dipterous faunae are to be considered as 

 branches of this stock, the necessary inference would be that at a for- 

 mer period Europe and America had a continental connection. Are 

 the Amber-diptera preserved fragments of this common stock ? Did a 

 continental connection between Europe and America really exist at the 

 time when they lived ? Did the submersion of an Atlantis tear asunder 

 the branches of this stock ?" (Amber-d ipfera , p. 324.) 



In another passage Loew remarks, in regard to the resemblance be- 

 tween European and especially North American Diptera and those of 

 the Amber Fauna, that '' the relationship between certain species is so 

 strikingly close, that it naturally suggests the idea of a genetic connec- 

 tion, and maintains it against all possible theoretical objections The 

 impression that the living species, connected by such a close link of 

 relationship to some Amber Diptera, are not new additions to the num- 



