260 HISTORY OF BRITISH FERNS. 



are emptied into the western ocean. These two longitu- 

 dinal divisions are subdivided transversely into provinces or 

 groups of counties, which together constitute the basin of 

 a principal river, or have some other physical peculiarity in 

 common. The mesial line is not continued northward of 

 Inverness, where Scotland becomes very narrow ; and the 

 portion of Inverness itself, eastward^ of Loch Erricht, is 

 united with the East Highland province. In like manner, 

 the extreme north of Lancashire is united with the Lake 

 province. The accessible information with reference to 

 Ireland is very imperfect. 



The facts embodied in the following pages are derived 

 from the principal published lists of localities (among which 

 it is hardly needful to say that the ' Phytologist' and Mr. 

 Newman's ' History ' stand pre-eminent in this respect) ; 

 from the habitats preserved in the herbariums of the Bo- 

 tanical Societies of Edinburgh and London (the contents of 

 the former having been obligingly communicated by Mr. 

 Lawson) ; from our own herbarium and observations ; and 

 from several local lists kindly furnished by the gentlemen 

 whose names are quoted. We are also indebted to H. C. 

 Watson, Esq., for many valuable notes, corrections, and 

 suggestions, by the aid of which our list is rendered much 



