yin 
PREFACE. 
true botanist can wait for more exact and comprehensive ac- 
quaintance with characters which do, and do not, distinguish 
species : and when, by experience, he is able to determine such 
marks, imaginary species fall back into the ranks of varieties ; 
or he is able, with the confidence of accurate observation, to 
pronounce that a true species, which by others may have been 
incorrectly regarded as a variety of some other form. 
The species recently observed in Derbyshire are twenty- 
two, all of which are figured in this volume : there are a 
few species and genera which might have been looked for, 
especially in the more elevated parts of the county, and 
which may even yet reward the exact scrutiny of perse- 
vering search. Such are Hymenophyllum — the H. Ton- 
bridgense * * * § and H. Wilsoni f — 
our Filmy Ferns , which creep 
over the surfaces of wet rocks, 
and resemble J ungermannias 
more than Ferns : — Crypto- 
gramma crispa, and Asplenium 
septentrionale , alternifolium, and 
lanceolatum ; Polypodium The- 
lypteris also, and Lastrea rigida, 
may have escaped observation.§ 
But it is more probable that the 
inroads of improvement in agri- 
* “On the hills, from Macclesfield to Buxton, on mossy rocks.” Mr. Bradbury, 
in Botanist's Guide. 
f H. Wilsoni is in Dr. Garner’s List of Staffordshire Plants, as occurring at 
Gradbich, near Flash, within a few miles of Buxton. 
§ Chinley Hills, near Chapel-en-le-Frith, are given in the “Botanical Guide,” as a 
locality of Cryptogramma crispa. The plant occurs in similar situations in Cheshire 
and Lancashire. Its English name, “Parsley Fern,” correctly describes the ap- 
pearance of this species. 
