FLORA. 27 



baccata, and certain willows, together with other plants 

 which occupy now an immense area in longitudinal extent, 

 show no other cause for their present diffusion ; and their 

 established presence, or at least that of their direct 

 homologues, in the Arctic tertiary vegetation, is a happy 

 confirmation of this view. It is thus that the studies of 

 Professor Heer have brought to light the geological titles 

 of many European and Asiatic species, which one would 

 have been ready to believe Autochthones, and which are in 

 reality only colonists and strangers of whom circumstances 

 in days of old have favoured the introduction.' 



Much interesting information is given in regard to Arctic 

 vegetation of the tertiary period, and in reference to 

 remains obtained from various localities it is remarked : 

 ' The unity of this flora, considered as a whole, and the 

 considerable proportion of species common to different 

 regions, notwithstanding the distance by which they are 

 separated, and the difference in their latitudes, testifies 

 that this corresponds to one and the same period, during 

 which, whatever duration it may have had elsewhere, the 

 Arctic vegetation, and the climate to which that vegetation 

 was subjected, have experienced but slight variations/ 



Many of the same plants are found in the miocene strata 

 in Europe, and in reference to plants of the same kind 

 now confined to the southern parts of Europe and of North 

 America, there is supplied the following table of successive 

 links connecting the vegetation of the Polar cretaceous 

 period with that of the present time : 



