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there, instead of which, they all curve gradually round, in a more or less concen- 

 tric fashion, and other trees occupy the intervening ground. These well-marked 

 features of forest distribution show that the present divisions of prairie and 

 woodland are of very ancient date. The evidence of the smaller plants, and also 

 of certain superficial geological conditions, all point to the same conclusion. 



The State of Minnesota is situated in a very interesting region in regard to 

 forest distribution. Here we find the northern limit of the group to which the 

 most southern trees of Ontario belong, such as the black walnut, shell-bark hick- 

 ory, hackberry, and Kentucky coffee tree ; the north-western limit of the com- 

 moner trees of the northern states and of Quebec and Ontario, such as white oak, 

 red cedar (arborescent variety), iron wood, beech, hemlock, white ash, rock elm, 

 red oak, yellow and black birch, sugar maple, red maple, wild plum, etc. The 

 western boundaries of some of the trees whose northern limits pass through 

 Northern Ontario, such as the white cedar, black ash, white pine and red pine ; 

 the southern limits of the most northern group, including the white spruce, the 

 large Banksian pine, balsam fir, balsam poplar and canoe birch ; and the general 

 eastern limits of some of the western species, such as the ash-leaved maple, 

 green ash, burr oak, and cottonwood. 



It will be observed that in Labrador peninsula the tree-lines tend northward 

 midway between the eastern and western shores. This is due partly to the 

 unfavorable influence of the sea on either side, and partly to the beneficial effect 

 of the central depressions in which the rivers run northward into Ungava Bay. 



From Mingan to Lake Superior, the height of land, north of the St. Law- 

 rence, is rudely parallel to the general course of the lines marking the northern 

 boundary of the trees. And it may have had some effect in limiting the north- 

 ward range of a number of species. A southward curve in the watershed about 

 the longitude ot Ottawa is marked by a corresponding curve in the tree lines. 

 Again, where a great depression occurs in this dividing plateau, some of the trees 

 which in such cases may be approaching their northern boundaries, are found to 

 extend, in the lower levels, beyond their general outline on either side. As 

 examples of this the Lake Temiscaming and Abittibi District, and the valley of 

 the Kenogami, or principal south branch of the Albany, may be mentioned. 



On the Missinaibi, or west branch of the Moose Eiver, the white elm reap- 

 years, 130 miles north of its general boundary on descending to a sufficiently low 

 elevation above the sea. The Saguenay, for about 100 miles from the St. Law- 

 rence is really a narrow arm of the sea, and the country in the vicinity of Lake 

 St. John at the head of the river, is only slightly elevated above its level and has 

 a fertile soil, although surrounded by a mountainous region. Here we find an 

 isolated colony of basswood, sugar maple and other trees, considerably removed 

 from the rest of their species. On the north side of Lake Huron, and to the 

 north of the City of Quebec, the land rises somewhat rapidly, and . in both 

 instances the tree lines near these latitudes are more closely crowded together 

 than elsewhere. 



Some kinds of trees, in approaching their northern limits, show a tendency 

 to diminish gradually in size, and to become more and more scattered, rendering 

 it difficult to draw any definite boundary of the species, while others vanish 

 abruptly. The latter habit is more characteristic of southern than northern 

 species so far as the Dominion is concerned. The various species appear to die out 

 more gradually as they range northward in the western than in the eastern 

 regions. 



