ECOLOGY OF ISLE ROYALE. 171 



general results thus far obtained regarding the geographical •dlstributiO'n of 

 Coleopterous insects in the territory of our republic. 



"The whole region of the United States is divided by meridional or nearly 

 meridional lines into three, or perhaps four, great zoological districts, dis- 

 tinguished each by numerous peculiar genera and species, which, with but few 

 exceptions, do not extend into the contiguous districts. The eastern one of 

 these extends from the Atlantic Ocean to the arid prairies on the west of 

 Iowa, Missouri, and Arkansas, thus embracing (for convenience merely) a 

 narrow strip near the sea-coast of Texas. This narrow strip, however, belongs 

 more properly to the eastern province of the tropical zoological district of 

 Mexico. 



■'The central district extends from the western limit of the eastern district, 

 perhaps to the mass of the Sierra Nevada of California, including Kansas, 

 Nebraska, Utah, New Mexico, Arizona, and Texas. Exgept Arizona, the entomo- 

 logical fauna of the portion of this district west of the Rocky Mountains, and 

 in fact that of the mountain region proper, is entirely unknown; and it is 

 very probable that the region does in reality constitute two districts bounded 

 by the Rocky Mountains, and southern continuation thereof. 



"The western district is the maritime slope of the continent to the Pacific, 

 and thus includes California, Oregon, and Washington territories. 



"These great districts are divided into a number of provinces, of unequal 

 size, and which are limited by changes in climate, and therefore sometimes 

 distinctly, sometimes vaguelj' defined. 



"The Atlantic district may be divided into: 1, a northern province, including 

 Maine, Eastern Canada, Nova Scotia, Newfoundland, etc., and extending west- 

 wardly from Lake Superior to Lake Winnipeg and Western Canada, which fades 

 insensibly into the great Arctic district; 2, a middle province, limited westward- 

 ly by the Appalachian chain, and extending to Southern Virginia; 3, a western 

 province, including Minnesota and the States of the valley of the Mississippi, 

 as far as the State of that name; 4, a southern nrovince, including the States 

 south of Virginia and Kentucky; 5, a subtropical province, including the point 

 of the peninsula of Florida; 6, a subtropical province, including the sea-coast 

 of Texas. 



"The Central district, as far as known, may be thus divided: 1, a northern 

 province, comprising the regions north of the Missouri, the plains of the Sas- 

 katchewan, etc.; 2, a middle eastern province, divided into two subprovinces, 

 including: a, Kansas, and Nebraska; b, northeastern New Mexico; 3, a south- 

 eastern province, including Texas, with the exception of province six of the 

 Atlantic district; 4, a southwestern province, including the upper part of, the 

 valley of the Gila; and 5, a south-southwestern province, including the lower 

 Gila and Colorado. The unexplored portions of this district will indicate middle 

 western, and northwestern provinces, or perhaps the necessity of constituting 

 with them and the southwestern province a district to be called the Interior 

 district. 



"The Pacific district may be divided as follows: 1, a hyperborean province, 

 consisting of Sitka and the neighborhood; 2, a northern province, including 

 Eastern Oregon and Washington; 3, a middle province, including Cali- 

 fornia, probably as far south as Santa Barbara; 4, a southern province, 

 including California from Santa Barbara to San Diego, extending to the crest 

 of the Sierra. Southern, or lower California is also, perhaps only In part, a 

 province of this district;* but, as yet, no collections of magnitude have been 

 received therefrom. Other provinces will, from the peculiar method of distri- 

 bution of species in that portion of America, be defined when more full collec- 

 tions are made, but at present cannot be indicated. 



"At the north, the Atlantic and Central districts seem to merge imperceptibly 

 together, about the valley of the Athabasca, and Winnipeg rivers, and finally 

 to disappear in the limited Arctic fauna; the hyperborean province of the Pacific 

 district also fares into this Arctic fauna, without, however, losing itself so 

 perfectly in the northern provinces of the other districts. We have thus evi- 

 dence that the American Arctic district may be divided into two provinces, an 

 eastern and a western. 



* " A few species, collected by John Xantus, Esq., at Cape San Lucas, though all new indicate a 

 greater resemolance to the fauna of the lower Colorado, tnan to that of maritime California- this 

 province may therefore be found eventually to belong to |the interior district." 



