Classification 
Writers upon British Ferns are not at all agreed as 
to their correct classification ; nor, in the case of many 
species, have they adopted the same names. The usual 
plan, and the one which has been followed here, is to 
divide them into three principal Groups, which are 
again sub-divided into the various Genera and Species. 
In the following pages are described, first the dis¬ 
tinctive features of each Group; then those of each 
Genus belonging to that Group ; and lastly those of 
each Species belonging to that Genus. It is chiefly 
by the arrangement and description of the sori, indusia, 
and veins, that the Group and Genus of any fern is 
determined. 
In the case of perfect and mature fronds identifi¬ 
cation is easy even for beginners; but it is often 
impossible for anyone to name young or seedling 
plants with accuracy. The table, page 53, will be 
found of assistance in distinguishing between some of 
the species which most resemble each other. 
The three principal Groups into which British Ferns 
are divided, are — 
I. Polypodiacee. 
II. OsMUNDACEE. 
III. 0 ph10glossacee. 
Polypodiaceae contain 16 Genera ; Osmundacese 1 
Genus ; and Ophioglossaceae 2 Genera. These are 
again sub-divided into various Species. 
