12 



some way or other to the countries whence the different types 

 were derived by transmission either over continuous or con- 

 tiguous land, or where such did not exist, by other adequate 

 means of diffusion. 



Let us then very generally, for we need not, even did time 

 permit, enter into minute details, apply this theory to the origin 

 and distribution of our alpine flora, and see what grounds there 

 are for its adoption in this particular instance. Now assuming, 

 as we are sufficiently warranted in doing from their similarity, 

 that the boreal flora of Great Britain had its origin from that of 

 Scandinavia, the specific centre whence it was derived, by what 

 means was it conveyed across the wide expanse of intervening 

 sea to its present habitat ? This, it is evident, could have been 

 effected only at a period when there was some connection of one 

 kind or other between the mountains of Scandinavia and those 

 of Britain. 



We have no grounds for inferring that the two regions were 

 ever at any time connected by continuous land or a mountain 

 barrier, as was the case between other portions of our islands and 

 continental countries. True there can be no question that the 

 East Coast of Scotland once extended farther into the sea than 

 now, as evidenced amongst other things by the remains of peat 

 mosses buried beneath the waters and covered by the sands ; and 

 there can be little doubt that the Scandinavian coast was also at 

 one period extended farther westward, of which the numerous 

 islands on the W. of Norway are the mementoes. But they 

 never seem, at all events, in any suitable epoch, to have been in- 

 timately connected by dry unbroken land, across which the flora 

 might have been transported. Nor even had they been so, would 

 this sufficiently account for the similarity of the plants of the 

 Scottish mountains and those of N. England and Wales. For 

 between these three also it is very evident that a connection dif- 

 ferent from the present must have existed before they could have 



