Cistopteris. ] 
FERNS. 
2.0 
Sit. — On rocks in the north of England and Wales ; also in Scotland. 
IIab. — Ben Lawers, Perthshire, Mr. R. Maughan. Cader Idris, and on rocks 
near Wrexham, Mr. J. E. Bowman. Rocks near Barmouth, Mr. Burton. Snow- 
don, Mr. C. C. Babington. Craig Breidden, Montgomerysh., Rev. A. Bloxam. 
Castle Dinas, Mr. W. Leighton. Common about Settle, Mr. J. Tatham, and Mr. 
Charley. (1. On lofty hills in the North, Sir J. E. Smith. Near Llanberris, 
Caern., Mr. Lloyd. Cordate, in Craven, Mr. Ctirlis. Downton, in Herefords. 
Geo. — Common in Germany, Switzerland, Dauphiny, Prussia, Holland, 
Verona, &c. 
2. — CISTOPTERIS FRAGILIS. 
BRITTLE BLADDER-FERN. 
(Plate II, fig. 2.) 
Ciia. — Frond twice-pinnate, lanceolate. Pinnae lanceolate. Pin- 
nules ovate, pointed, deeply cut, toothed, decurrent. 
Syn. — Cystea fragilis, E. FI . — Cistopteris fragilis, Hook., in Br. FI., Mack., 
Bernh . — Aspidium fragile, Swz., Hook, in FI. Sco., IVilld., Grev., Light/. 
Polypodium fragile, fVith., Linn., Huds., Boll., Hoffrn., Ehrh., IHck . — 
Cyathea fragilis, Roth., Smith in E. B. eye. Gulp . — Cyclopteris fragilis, 
Schrad., Gray. 
Fig. — E. B. 1587 .—Bait. 45-4G.— Flo. Dan. 401. 
1)es. — Root black, fibrous, and tufted. Fronds numerous, de- 
ciduous, bright green, from 6 to 12 inches high, twice pinnate, lan- 
ceolate, pointed, and finely tapering towards the apex. Rachis very 
brittle and shining, of a dark brown or black colour on the lower 
part, and quite smooth, except a tuft of scales at the very base. 
Pinnae opposite, pointed, about twenty pairs, confined to the upper 
half of the rachis, and growing nearly at right angles to it. Their 
length more than twice their width, except the lower pair, which 
are also distant from the next above them. Pinnules alternate, 
acute, deeply lobed, crenate or bluntly acute, decurrent and tapering 
more or less at the base. Sori numerous, confluent, black when 
young, afterwards a shining brown, and found throughout the 
summer. Indusium white, with an irregular margin, and soon 
obliterated or thrown off by the growing thecte. 
In general habit resembling the last species, but instantly to be distinguished 
by the shape of the frond, which is sharper and longer pointed, as is also the case 
with the pinnae and pinnules ; the whole is also much more divided, all the larger 
pinnules being cleft, and not merely toothed, as in every state of Cistopteris 
dentata. The stem is also darker, longer, and more brittle, and the sori so 
numerous as soon to become confluent. 
No Ferns are more altered by circumstances than this genus, hence the difficulty 
of distinguishing the species. The varieties, however, are not distinct in them- 
selves, as they may all sometimes be found upon the same plant, and different 
seasons produce differently-shaped and more finely-divided fronds. For example, 
those which arise in ordinary seasons alone answer the above description ; a cold 
