418 Canadian Record of Science. 



at first appear to indicate that the immigration had an 

 eastward flow from Asia rather than a mingling of both 

 American and Asiatic floras. It might, however, be sup- 

 posed to prove that the migration was only from Japan and 

 the Siberian coast, and was entirely by the Japan current, 

 the direction of which is towards Alaska and then down the 

 Alaskan and British Columbian coasts, any exceptions to 

 the course of this migration being due to exceptional causes. 

 Or, when the fact is considered that out of towards four 

 hundred species, which in Canada do not range east of the 

 Rockies, and mostof which do not extend north into Alaska, 

 the two coast forms already referred to, Calystegia soldanella 

 R. Br., and Rubus spectabilis, Psh., and a rare few, which 

 like RJrythronium grandiflorum, Psh., and Epipactis gigantea, 

 Hook, will no doubt be found in British Columbia, alone 

 likewise occur in Japan, it may rather indicate that the 

 British Columbian flora is of more recent age than the 

 general and northern floras of the Dominion, or, at any 

 rate, that its occurrence in British Columbia is of more 

 recent date than the period when the intermingling of 

 American and Asiatic plants took place. British Columbia 

 is. geologically speaking, recent. The Rocky Mountain 

 region has, at least in the United States, considerable thick- 

 nesses of both Miocene and Pliocene strata, and it is there- 

 fore certain that the great disturbances which resulted in 

 the final elevation to their present height of these huge 

 mountain ridges which parallel the western coast of North 

 America, took place about or after the close of the Tertiary 

 period. We can even conceive it possible that some of the 

 same great convulsions which produced these mountain 

 chains - one of which extends to the extremity of the 

 Alaskan peninsula — may also have resulted in the severing 

 of the connection between Asia and America, and the crea- 

 tion of the Aleutian and neighbouring islands, where for- 

 merly mainland existed. That the present flora of the 

 northern part of this continent was in existence at the close 

 of the Tertiary period, there is little doubt. It was well 

 established at the deposition of the Leda clays of Quebec, 

 and at that time there were many representatives there 



