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 FERN". 



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 



