CTSTOPTERIS MONTANA. 123 
CYSTOTTEKIS MONTA'NA. 
THIS has long been known as a Fern of the highest 
alpine districts of Europe, North America, and 
Kamtschatka ; but it was not until 1836 that it was 
ascertained to be a British species. In that year it 
was discovered by Mr. W. Wilson on Ben Lawers, 
one of the Bredalbane Mountains. 
It has been called by botanists Polypodium montanum 
and myrrhidifolium, Aspidium montanum, Cystopteris 
montana and myrrhidifolia. and Cyathea montana. In 
English it is known as the Mountain Bladder Fern, and 
Wilson's Bladder Fern. 
The root is thread-like, scaly, black, and far-creeping, 
f he fronds strikingly triangular in their outline. Their 
stalk long, stout, green, and smooth, except near the 
bottom, where there are some scattered brown scales. 
The leaflets are alternate, and occupy only the upper 
third of the stalk. The lowest pair of leaflets are very 
much larger than the others, and doubly-leafited ; but 
the leafits of the upper pairs of leaflets are only deeply 
lobed. The lateral veins of the leafits are alternate, 
and the fructification is at the ends of these lateral 
veins. The masses are circular, numerous, and become 
very prominent as they ripen. The membrane (indusium) 
is nearly round, forming a hood over the spores, and 
having its edge jagged. 
Mr. Moore observes that 
" Thb head-quarters in Britain of this very rare and local 
