80 V. CYSTOPTEBIS. 
each marginal tooth. The son are borne towards the mar- 
gin, and are often numerous but not crowded, and I believe 
never confluent ; they are small and roundish, with a white 
membranous concave indusium attached by its base towards 
the base of the lobes, having a free more or less jagged 
point. 
This species has now but slight claims to be regarded aa 
a British fern ; its only authenticated habitat is a wall at 
Low Layton, in Essex, where it was originally found, near 
the close of the last century, in great plenty, by Mr. Forster. 
Repairs of the wall have, however, nearly eradicated the 
plant, though it has within the last few years been found 
there and in the neighbourhood spaiingly. Mr. Shepherd, 
of Liverpool, has sent me specimens of C. alpina, said to 
have been gathered in Derbyshire and Yorkshire, but with- 
out assigning more particular habitats. Scotch and Welsh 
alpine stations which have been assigned to this species 
probably belong to some of the small much-divided forms 
of C. fragilis. C. alpina is distributed over the Alps of 
Europe, chiefly in the south. 
It may be cultivated precisely in the same manner as 
Cystopteris fragilis. 
3. Cystopteris mon tana, Link. Mountain Blad- 
der-fern. Fronds triangular tripinnate ; pinna- spreading 
ultimate pinnules narrow oblong or obtusely sub-falcate 
inciso-dentate or pinnatifid, the lobes toothed at the apex 
rachis not winged. 
CTSTOPTEBIS MONTANA, Link : Hook. Sp. FiL L 200 : Hook, aud 
Arn. Fl. 572: Florig. Brit iv. 88: Newm. 159: Bab. Man. 413. 
CYSTOPTEBIS ALLIOM, Newm. App. xxv. POLTPODIDM MONTANUM, 
Allioni. CTATHEA MONTANA, Roth. ASPIDICM KONTAKUM, 
Swartz. 
The Mountain Bladder-fern is well distinguished by its 
small triangular fronds, which in shape resemble those of 
Polypodium Dryopteris. It has a long creeping filiform 
8caly caudex, to which the fronds are either terminally or 
laterally adherent The stipes is long, slender, erect, red- 
