38 TRANSACTIONS OF THE CANADIAN INSTITUTE. [Vot. VIII. 
is less near the United States boundary line than farther north, due to 
the more numerous mountain heights commencing with the Vancouver 
Island range which intercept the moisture laden clouds on their way 
across British Columbia from the ocean. The plants of this group do 
not range east of the Rocky Mountains. 
PLANTS COMMON TO EUROPE AND AMERICA. 
That there is a considerable resemblance between the floras of Can- 
ada and Northern Europe and again between the floras of Canada and of 
Eastern Siberia and Japan, is well known. Including the Horsetails and 
Ferns, probably about 575 species are common to Canada and Europe, 
and, again, probably nearly 350 are common to Canada and Japan or the 
River Amur country. A large number of these in turn are common to 
the three continents or are represented by varieties which have, no doubt, 
their origin in the changed environment. The hypothesis, generally 
accepted, has been that in some comparatively recent epoch there had 
been a connection between Europe and America which had facilitated 
the intermingling of the plants of the two continents. The late Profes- 
sor Asa Gray, of Harvard University, however, suggested the probability 
that the migration of European plants had taken place across Asia to 
America. I have not been able to follow the conclusions of others on this 
subject. The peculiarities in the range in Canada of these Asiatic and 
European species, the identity of many of the fossil plants found in the 
Pleistocene clays in Canada with plants now existing on the three con- 
tinents, and the older look of this northern part of the American con- 
tinent, all seem rather to suggest that whilst there may have been facili- 
ties for migration to this continent both in an easterly and westerly direc- 
tion, Canada was the point of origin of many species now common to 
Europe and America. There are numerous European species in the 
eastern half of Canada which are unknown to the western half and yet 
are represented in Eastern Siberia and Japan. How can this immense 
gap be accounted for? Again, there are other European species similarly 
limited to the eastern half of this country and which do not occur in either 
Siberia or Japan. This is also an anomaly. The argument of range is 
somewhat lengthy and will not be gone into here. It has, however, 
been supplemented by geological discoveries in recent years, for in- 
stance, of over seventy fossil plants in the Pleistocene clays of Toronto, 
Ottawa and elsewhere. Of these, twenty occur at the present day in 
both Europe and Canada, fourteen are similarly Asiatic and Canadian, 
whilst eleven are common to the three continents. This, if it does not 
indicate that in Pleistocene times the intermingling of American, Asiatic 
and European forms had already beeen effected, at least shows that in 
