BRITTLE FERN. 
153 
in any degree imperfect to some established species, expressing 
a doubt if I entertained one, than separate such imperfect spe- 
cimens under a new appellation. In every attempt I make to 
establish or ascertain a species, I find it most satisfactory to dis- 
miss entirely all such specimens, to refuse all cognizance of 
them, and to contrast the most perfect and most fruitful fronds 
only. For as in Zoology we find specific differences most satis^ 
factorily developed in adults, so shall we also find in ferns ; and 
if essential differences really exist, we shall be sure to see those 
differences more clearly when Nature has brought the objects 
under consideration to their highest state of perfection, maturity 
and beauty. Entertaining these views, I have dismissed from the 
enquiry — as regards the species of Cystopteris — not only all 
seedling, immature, barren or monstrous fronds, but also all those 
which appeared to owe their peculiarities to the varied degrees 
of drought or moisture, elevation, protection or exposure, or the 
numerous other casualties to which so hardy yet fragile a fern 
is by its nature subjected ; and to compare those only which 
grew under corresponding circumstances, had arrived at a 
corresponding state of maturity, and possessed the stem entire 
to its very junction with the rhizoma. The result of a very 
careful scrutiny may be thus summed up. First, I think it 
highly probable that many species are confounded under one 
specific name. Secondly, I am unable to give my assent to the 
species described by Sir J. E. Smith; neither his published de- 
scriptions nor the authentic specimens named by himself suffi- 
ciently exhibiting specific differences. Thirdly, I consider that 
forms exist quite as marked and as distinct from the normal or 
usual form of fragilis as any that have hitherto received names, 
either as species or varieties. And fourthly, I find myself un- 
able to lay down characters whereby any individual form may 
be clearly and distinctly ascertained. Under these circumstan- 
ces I prefer treating them still as constituent parts of a single 
species, leaving the task of separation to abler botanists than 
myself, but giving the whole of Smith’s descriptions at length, 
accompanied in every instance by the figure of a frond, carefully 
compared with the specimens from w^hich his description was 
compiled. 
