220 [September 



If it had so happened that the variety of Antiopa with a white bor- 

 der to its wings was peculiar to North America, instead of being pecu- 

 liar to England, how eagerly the fact would have been seized on by 

 Prof. Agassiz and his school, as a proof that the supposed American 

 variety was a distinct species ! Truly says Loew, that forms which, if 

 they had been found in Europe, would certainly have been considered 

 as only slight varieties of other well-known European species, as their 

 only deviation consists in a slight difference of coloring, when found in 

 America are immediately pronounced to be distinct species. {Amher- 

 diptera, p. 318.) 



To investigate the probability or possibility of each particular insect, 

 claimed to have been introduced into North America, having been in 

 reality so introduced, would, however, be an endless task. It is suffi- 

 cient to remark that if one single species, of the 304 asserted by various 

 authors to be common to the New and Old Worlds, is indigenous in 

 each of these two habitats, then, as a necessary consequence, the asser- 

 tion of Prof. Agassiz, that our insect Fauna "differs specifically through- 

 out" from that of Europe, falls to the ground. 



It may be asked why Agassiz should have asserted so confidently 

 that all the insects of the temperate zone of North America differ spe- 

 cifically from those of Europe. The answer is, that he believes in the 

 theory of many contemporaneous local creations, or to use his own lan- 

 guage, " that animals must have originated where they live, and have 

 remained almost precisely within the same limits ever since they were 

 created, except in a few cases, where, under the influence of man, those 

 limits have been extended over large areas." (^Lake Siqierior, p. 248.) 

 Let us see where such a theory will lead us in the case of the geogra- 

 phical distribution of Coleoptera within the limits of the United States. 



" The whole region of the United States," says Dr. LeConte, " is 

 divided by meridional or nearly meridional Unes into three, or perhaps 

 four, great zoological districts, distinguished each by numerous peculiar 

 genera and species, which, with few exceptions, do not extend into the 

 contio-uous districts. The Eastern one of these extends from the At- 

 lantic Ocean to the arid prairies on the west of Iowa, Missouri and 

 . Arkansas. * * The Central District extends from the western limit of 

 the Eastern District perhaps to the mass of the Sierra Nevada of Call- 



