CYSTOPTERIS. 
175 
warmer parts of Great Britain and Ireland, evidently 
preferring cavernous and rocky situations within the 
influence of the sea. The same species is found in the 
warmer parts of Europe, in Asia, in the north of Africa, 
and in the Canaries and Cape de Verd Islands. 
It is, moreover, a tender plant, and does not thrive 
under cultivation in the climate even of the south of 
England, unless sheltered in a frame or greenhouse, or 
by being covered with a glass. In a Wardian case it 
grows well; and attains great luxuriance in a damp hot¬ 
house. The proper soil for it is very light turfy peat, 
mixed with a considerable proportion of silver sand, and it 
is beneficial to plant it on or around a small lump of free 
sandstone. 
Genus XIII. CYSTOPTERIS, or BLADDER PERN. 
The species of Cystopteris are all small fragile Ferns, 
yet, notwithstanding, they are very beautiful and very in¬ 
teresting, and furnish some remarkable differences of form. 
They are much more delicate and herbaceous in their 
texture than the majority of our native species, and hence 
