FORESTS AND TREES OF NORTH AMERICA. 271 



limit of forest growth. It is laid down from the information given 

 Ly Eichardson, Belcher, and other arctic explorers, and is one of the 

 best defined boundaries of organized beings on the continent. North 

 of it there are no trees and but few woody plants ; the vegetation is 

 mostly peculiar ; and the animals, numerous in species, in but few 

 instances extend south of it. Both are generally identical entirely 

 around the north pole, and this therefore forms part of the Arctic 

 Province; while many peculiar species as well as marked geographical 

 boundaries separate it Irom the Asiatic portion and, it may be called 

 the Esquimaux Begion. This line coincides well with the yearly 

 isothermal of 17° 5', summer 50°, winter — 15°, in all that portion 

 between Hudson bay and the Mackenzie river, but it seems probable 

 that other circumstances besides temperature regulate the forest limit 

 near the east and west ends. Neither the climate nor vegetation of 

 these parts is yet well enough known to admit even of speculations on 

 this subject. 



A, B, and C, may, together, be considered as forming a Province, 

 which, from the number of its great lakes, may be called the Lacusti'ian. 

 It is well characterized by its forests, almost unbroken, consisting 

 chiefly of evergreen Corifera, which afford food and shelter to a large 

 number of characteristic animals. It comprises most of the fur coun- 

 tries of North America. It is only near the Alleganies that its limits 

 are obscure, but the broken lines there indicate the average range of 

 its characteristic species. The next line southward is 3 — 4, running 

 nearly parallel to 1 — 2, and separating the water-sheds of Hudson Bay 

 and the Gulf of St. Lawrence from the basins of the Great Lakes and 

 Lake Winnipeg. It forms the northern limit to a large number of 

 trees, &c., but can only be considered approximate towards its eastern 

 end. It corresponds very well with the isotherm of 37° 5', summer 

 G0°, winter 15°. The careful observations of Richardson at its 

 western end show that there are about 24 species of trees common 

 north of it, while many cease to grow very abruptly in the vicinity of 

 Lake Winnipeg. 



The country between 1 — 2 and 3 — 4 is divided for convenience into 

 two regions, A the Algonquin, and B the Athabascan. Though the 

 peculiar products of each are little known, there seem to be indications 

 even among the trees of considerable difference, especially in the 2^^^- 

 'portions. The Algonquin is almost unexplored, but will probably be 

 found to have the greatest numbers of several of the trees mentioned 

 in the catalogue, as most abundant in adjoining regions ; none are, 

 however, peculiar to either of these northern regions. 



The line 5 — G is used to bound approximately the Canadian Begion 

 on the southeast, though from the nature of the country there is no 

 well marked division there, the valleys belonging to one region and 

 the mountains to the other. 



The numbers 5 — 6 — 7 indicate the general limits of D, the Alle- 

 ghany Begion comprising the eastern slopes, and towards the south, 

 some of the highest peaks and ridges of this range ; 24 trees are con- 

 sidered characteristic, and G peculiar to it. Towards the west and 

 south its limits are not well marked from the uneven surface of the 

 country, but to the southeast the line between it and G is the abrujit 



