184 HISTORY OF BRITISH FERNS. 



vein is somewhat flexuous, and gives off alternate lateral 

 veins, one of which is directed towards the sinus or margi- 

 nal indentation between two serratures. The sori have the 

 roundish form common in this genus, and, being often 

 numerous, they then become very conspicuous when full- 

 grown ; but though crowded, they do not appear often to 

 become confluent. These sori are covered, in the young 

 state, by blunt, concave, jagged-edged indusia. 



This rare species was supposed to occur wild in the 

 United Kingdom only, among the Breadalbane mountains 

 of Scotland, on one of which, Ben Lawers, it was originally 

 found in 1836 by Mr. Wilson, in company with Sir W. J. 

 Hooker and Professor Graham. It has subsequently been 

 found in other parts of the same region ; and more recently 

 by Mr. Backhouse in the Clova Mountains. It grows in 

 very wet shady places, on the ledges of the rocks. In the 

 European Alps this Fern is met with, most abundantly 

 northwards ; and it also occurs on the Eocky Mountains 

 of the New World. 



The synonyms of this species are Pohipodium montanum, 

 Aspiditim montanum, Cifathea montana, Cystopteris Alli- 

 oni, and Cystopteris myrrhidifolia. 



