GEOGRAPHICAL DISTRIBUTION. . 1£5 
The extreme range of the thermometer extends from 
38° below zero, Fahr., to 100° above, making one hun- 
dred and tliirty-eight degrees ; and the mercury often 
remains below zero for many days together. The sum- 
mer heat, though never long continued, is excessive. 
The prevailing rocks west of Lake Superior are primary, 
the soil is thin and poor, and the vegetation stunted. 
Operated upon by these causes, the species which pre- 
vailed in the preceding section become less and less 
numerous as the secondary region east of Lake Superior 
runs out farther west, and finally disappear. The genus 
Vltrina is, however, indigenous to it, and Helix inornata, 
which is believed to reach a more northern as well as a 
more elevated position than any other species, is also 
found in it. Here appears also the singular little Bul- 
i m us liarpa, which is unknown farther south. This sec- 
tion is but little known. 
Section 6. The North-eastern Section. This lies 
between the St. Lawrence River and the Atlantic Ocean, 
and comprises the northern parts of New York and Ver- 
mont, and all New Hampshire and Maine ; the British 
provinces of New Brunswick and Nova Scotia are also 
included within it. Its summers are short, and its win- 
ters long and severe, exhibiting extreme reductions of 
temperature, but modified by its proximity to the ocean. 
In Nova Scotia, which is almost insular, the winters are 
said to be much more mild than in the same parallel of 
latitude in Canada. In its general character, as affected 
by climate, the section resembles the preceding, and 
though separated from it by a great extent of interme- 
vol. i. 33 
