336 PHYSICAL GEOGRAPHY. 



Pezotettix borealis and P. mmica do not extend below the uppermost 

 boundaries of the blue belt ; while, among Alleghanian species, Trimero- 

 tropis cequalis, ArpJiia xantJwptcra, and A. sitlphiiira are limited on the 

 north by the red band, the first perhaps extending somewhat farther. 



But the principal interest attaching to the distribution of insects in 

 New Hampshire is through their relation to the White Mountains. These 

 mountains are situated next the southern boundaiy of the Canadian 

 fauna, and their valleys, as well as the lower wooded portions of their 

 slopes, are peopled with representatives of this region ; but their peaks 

 rise from above the limit of forest growth, and maintain a fauna and flora 

 very distinct from those below. 



It has long been known that in ascending lofty mountains within the 

 warm or temperate regions, one passes successively over areas exhibiting 

 in their vegetation distinct features, with an ever increasing resemblance 

 to more northern floras. The European Alps have furnished a field for 

 extensive investigations ; and their sides have been mapped into distinct 

 zones, called, on an ascending scale, the mountain, the sub-alpine, and the 

 alpine regions. These regions have been recognized and applied to 

 similar phenomena elsewhere, and are in general use. It has also been 

 noticed that the distribution of animals upon mountain summits corre- 

 sponds with that of plants. 



So far as plants are concerned, no distinctive alpine and sub-alpine 

 regions have yet been recognized in the White Mountains. Dr. Asa 

 Gray, it is true, in his statistics of the flora of the northern United 

 States,* gives separate and extended lists of alpine and sub-alpine plants ; 

 but the only distinction made between the two is, that the former are 

 found only in "our small alpine region" (in which he includes all the 

 treeless summits of the White Mountains), and the latter "occur mainly in 

 our alpine region, but are also found decidedly out of it ;" so that the lists 

 do not separate plants of distinct alpine and sub-alpine aoncs. Prof. E. 

 Tuckerman, in a very interesting article upon the vegetation of the White 

 Mountains,! says, — "Botanists designate the highest bald district, with 



* Amer. jTimrn. Arts and Sc. [2], x.\ii, 231; x.xiii, 62, 63. 

 t Tlie lyjiite Hills, by T. S. King, p. 232. 



