174 THE CANADIAN NATURALIST. [May 



pliocene epoch, and, it may be, to a more distant age. In the Leda 

 clays of Green's Creek, near Ottawa, occur numerous nodules 

 enclosing, among other organic remains, many fragments of plants. 

 Dr. Dawson has, after careful examination, identified Drosera rotun- 

 difolia Linn., Acer splcatum Linn., Potentilla Canadensis Linn., 

 Gaylussacm resinosa Torrey and Gray, Populus balsamifera' 

 Linn., Thuja occidental is Linn., Potamogeton perfoliatus Linn., 

 P. pusillus Linn., and Equisetum sewpoides Michx.J Now, it 

 will be noticed not only that all of these plants are of still existing 

 species, but also that four, Drosera rotundifolia, Potamogeton per- 

 foliatus, P. pusillus, and Equisetum scirpoides, are common to 

 Europe and America. This would appear to establish the fact, 

 irrespective of any evidence which may exist in other countries, 

 that the intermingling of European and American forms, so notic- 

 able a feature in our North American vegetation, took place either 

 during this epoch or at an earlier period. Still further evidence 

 of this is afforded by the inland maritime flora. No less than 

 eleven of these have a European as well as an American range. 

 Thus, a part of the temperate floras of both continents can mark 

 the dawn of its existence at a very early period in this epoch, and 

 probably during the antecedent age. 



All of our high northern forms occur either in the districts 

 fronting the Gulf and upon the shores of the Lower St. Lawrence, 

 or upon the coasts of Lake Superior. We have no mountains 

 known to us to be capped with little assemblages of arctic and sub- 

 arctic plants, since Mt. Logan and other considerable elevations in 

 the extreme eastern parts of Lower Canada, on which some may 

 be supposed to occur, remain as yet unexplored. The Island of 

 Anticosti, the Mingan Islands, and, it is to be presumed, the neigh- 

 bouring districts of the mainland on the northern coast, have a 

 nearly arctic aspect, while the north shores of Lake Superior are 

 as nearly sub-arctic in their floral characters. On the former occur 

 a number of characteristic arctic forms, but associated with many 

 plants of more temperate range ; and on the latter, whilst there are 

 sub-arctic species present, they are also accompanied by numerous 

 others which have an extensive diffusion to the southward. 



It is a circumstance to be somewhat expected, in consequence of 

 the difference of latitude, that the flora of the south shore of Lake 

 Superior, and of the north shore of Lake Huron, is much less 



| Canadian Naturalist, present volume, p. »'>;). 



