1864.] 221 



fornia; * * but it is very probable that this region does in reality 

 constitute two districts bounded by the Rocky Mountains. The West- 

 ern District is the maritime slope of the continent to the Pacific, and 

 thus includes California, Oregon and Washington territories. 



* * :ii ^ ^ ^ 



" The method of distribution of species in the Atlantic and Pacific 

 Districts, as already observed by me in various memoirs, is entirely 

 different. In the Atlantic District a large number of species are dis- 

 tributed over a large extent of country ; many species are of rare oc- 

 currence, and in passing over a distance of several hundred miles, but 

 a small variation will be found in the species obtained. In the Pacific 

 District, a small number of species are confined to a small region of 

 country ; most species occur in considerable numbers, and in travelling 

 even one hundred miles, it is found that the most abundant species 

 are replaced hy others, in many instances very similar to them. * * In 

 the Central District, consisting as it does to a very large extent of 

 deserts, the distribution seems to be of a moderate number of species 

 over a large extent of country, with a considerable admixture of local 

 species." (LeC. Col. Ks. and East. N. 3Iex., Oct. 1859, pp. iii — v.) 



Assuming the correctness of these data and of the theory of Agassiz, 

 it follows that there must have been at least three separate and distinct 

 coleopterous creations within the limits of the United States. Nay, 

 further. As on the Pacific slope, according to LeConte, every hun- 

 dred miles that you travel you come upon a new coleopterous fauna, 

 there must have been about twenty or thirty separate and distinct cole- 

 opterous creations there. For it is absurd to suppose that the Coleop- 

 tera, peculiar to each local district of 100 miles square, were formerly 

 common to the whole territory and have all taken their origin from one 

 common centre of creation. It would be as rational to believe, what 

 Agassiz scouts as absurd, that all the fiiunas of the whole world were 

 created simultaneously, with all their present specific and generic dis- 

 tinctions, in one common centre of creation, and thence spread them- 

 selves in locally distinct groups over the whole face of the globe, leav- 

 ing no trace behind of the path travelled over by them in arriving at 

 their present habitats. 



When we take into account that the same reasoning which applies 

 to North America applies also to other parts of the world, and that 



