140 THE CANADIAN NATURALIST. [June 



to 500 feet above the sea, watered by the Upper St. John and its 

 tributaries, the northern affluents of the Penobscot, and the River 

 Restigouche. A triangular plain expands from a point within 

 a few miles of the Maine boundary to a width of 150 miles or 

 more, where it passes beneath the waters of the Gulf of St. Law- 

 rence. This Lower Plain rarely rises more than 300 teet above 

 the sea. Between the upper and lower plain lies a broken country 

 rising into a knot of high hills in Northern New Brunswick. 

 Lastly, there is a series of parallel ridges in the south, forming a 

 hill-country of less altitude than the last, lying along the north 

 shore of the Bay of Fundy. About two-thirds of this region is 

 drained by the River St. John, which breaks from the level of 

 of the upper plain at the Grand Falls ; and, descending through 

 several rapids and quick-waters, reaches tide-level at the western 

 border of the lower plain, whence its course to the sea (distant 90 

 miles) is comparatively sluggish. 



The rest of the Maritime Provinces of Canada, consisting of 

 Nova Scotia and the twin islands of Prince Edward and Cape 

 Breton, may be comprised under the term Insular Acadia. 



Before describing in detail the peculiar groupings of species in 

 this region, it may not be amiss to mention a few of the agencies 

 which have given rise to the diversified forms of vegetation now 

 existing on the earth ; and then to add some remarks upon their 

 peculiar manifestation in that part of America to which these ob- 

 servations more particularly relate, and to show their influence 

 upon the range of plants within it. 



Of these agents perhaps the most important is Variation of 

 Temperature. It is well known that there are two directions in 

 which this variation occurs, one on going north or south from the 

 Equator, and the other in ascending from the level of the ocean 

 to the tops of mountains. In both of these the temperature 

 becomes lower in proportion to the elevation in the one case, or to 

 the distance from the equatorial circle in the other. This 

 decrease in temperature exerts so great an influence over plants 

 that few species are found to be common to places widely diflering 

 either in latitude or altitude. 



Soil is another influential agent in the limitation of species and 

 the modification of individuals ; some plants being peculiarly 

 adapted to certain kinds of soil, and rarely found growing in any 

 other, while others, although they may exist, present a puny and 



