The British ferns are widely distributed throughout 
the United Kingdom, occurring more or less abundantly 
from north to south and from east to west, except where 
local peculiarities are unfavourable to their existence. On 
the summits of our loftier mountains they occur but 
rarely, but here their comparative absence is to be attri- 
buted not so much to the actual elevation as to the bleak- 
ness of the situation, which condition is generally un- 
favourable to ferns. They are found, however, existing 
under a variety of circumstances ; and though undoubt- 
edly a calm and moist atmosphere is, in a general sense, 
most favourable to their development, there are but few 
species which are strictly confined to localities where 
these conditions prevail. When growing in drier and 
more exposed localities, they follow the law which affects 
vegetation generally, being in such situations smaller, 
more rigid in texture, and often less divided ; and it is an 
interesting inquiry, how far variations of appearance thus 
induced become permanently fixed characters, transmis- 
sible to succeeding generations. 
The limits of this volume do not admit of the distribu- 
tion of the British species being stated in detail. Some 
attempt, however, may be made to indicate their range 
by means of the tabular formulary inserted on the follow- 
ing pages (18-19). This table is constructed on the basis 
of Mr. Watson's ' ' Botanical Provinces," which we have 
also adopted in the Popular History of British Ferns, and 
of which a more detailed account may be found in Mr. 
Watson's valuable contribution to botanical geography, 
the Cybele Britannica. These provinces, as here adopted, 
have the following limits : (see page 20.) 
