393 X. GENERAL REMARKS. 



probably another recent importation into Ireland and Eu- 

 rope from tlie western hemisphere ; not constituting a true 

 link of connexion between their native floras. — -Potentilla 

 tridentata has been reported a plant of Scotland, only on 

 authority which English botanists have learned to dis- 

 trust where not confirmed. 



It thus appears to be quite true, that the British Isles 

 have either no species or extremely few species peculiar 

 to themselves ; all (others) being found' elsewhere in 

 Europe, with the very scanty exceptions above alluded 

 to. But the same species nowhere all meet within any 

 single political country or even well-defined natural divi- 

 sion of Europe ; and everywhere they are found inter- 

 mingled with other species which do not occur in Britain. 

 It would be necessary to include a long tract, taking 

 in all western Europe, from Spain to Norway, to make 

 out a country large enough to show all the British jplants, 

 after deducting the Eriocaulon and Spiranthes, and per- 

 haps Alopecurus alpinus, with other more doubtful species 

 and doubted natives. And ui that long space there 

 would be found a large number of non-British species 

 commingled with those common alike to Britain and 

 western Europe. The farther we recede from western 

 Europe, in any direction, the more do the British ele- 

 ments of the flora decrease in their proportions to the 

 non-British ; so that eventually, at great and unequal 

 distances, we find floras almost devoid of British species ; 

 and finally, in some considerable tracts, even quite devoid 

 of them. 



These gradual changes, these agreements and differ- 

 ences between the flora of Britain and the floras of other 

 parts of the Earth, near and remote, might be described 

 and explained in a ' British and Foreign Cybele,' which 

 would likely prove a contribution of much importance to 



