20 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



ferent from those of the arctic regions. Thus latitude and 

 altitude, as they affect temperature, and moisture or the lack of 

 it, exercise important influences upon the distribution of insects. 



In order to designate approximately the various natural areas 

 of the United States in connection with the distribution of 

 organisms, we speak of the Boreal, Austral, and Tropical regions. 

 Each region is further divided into zones, beginning at the 

 north, as follows: Arctic- Alpine zone, which is above the limit 

 of tree growth; Hudsonian, extending from Labrador to Alaska, 

 and including the northern portion of the great forests of spruce 

 and fir ; Canadian, comprising the southern portion of the conif- 

 erous forests, and the greater part of Canada, northern New 

 England, the Adirondacks and high mountains of the Alle- 

 ghanies, northern Michigan and Minnesota, and the higher parts 

 of the Rocky Mountain region. The Transition zone is considered 

 as marking the region where the Boreal and Austral elements 

 overlap ; and takes in most of the New England territory and the 

 Alleghanian region, extending across the northern part of the 

 United States, and includes also the greater portion of the Rocky 

 Mountain region except the low valleys and deserts, which belong 

 to the Austral, and the high mountains, which belong to the 

 Canadian zone. The eastern portion of the Transition zone, 

 which is humid, is often called the Alleghanian, in contradistinc- 

 tion to the more arid western or Pacific Coast Transition. The 

 Upper Austral zone extends along the coast from Southern New 

 England to Chesapeake Bay, and then southward each side of 

 the mountain region and westward through the Central States 

 and the valleys of the Rocky Mountain region. The eastern por- 

 tion is often called the Carolinian zone. The Lower Austral 

 extends from Chesapeake Bay along the coast to Mexico, and 

 includes portions of Arizona and southern California. 



Any one interested in these life zones, and the fauna, flora, 

 and agricultural crops peculiar to each, should procure a copy 

 of Dr. C. Hart Merriam's bulletin,* which explains the matter 

 more fully and contains a map showing the extent of each zone. 

 In order to show the relation of these zones to Connecticut, the 

 accompanying map (see Fig. i) has been adapted from Dr. 



*Life Zones and Crop Zones. Bulletin No. 10, Division of Biological Survey, U. S. 

 Dept. of Agriculture, Washington, D. C, 1898. 



