BRITISH FERNS. 31 



THE BRITTLE FERN. 



CYSTOPTERIS FRAGILIS. Bernhardi, Presl. 



Cistopteris dentata, fragilis, and alpina. Hooker, Francis. 



Cystea fragilis, dentata, angtistata, and regia. Smith. 



Polypodium fragile. Linneus, Hudson, Lightfoot, Berkenhout. 



Polypodium fragile and rhteticum. Bolton. 



Polypodium fragile, dentatum, and trifidum. Withering. 



Aspidium fragile. Sadler. 



Cyckpteris fragilis, Athyrium dentatum and regium. Gray. 



LOCALITIES. 



ENGLAND . . Northumberland, Cumberland, Westmoreland, not uncommon; Yorkshire, near 

 Richmond; Lancashire; Cheshire; Shropshire; Derbyshire, Matlock, Buxton, 

 Dovedale, and the Quadrangle of Haddon Hall ; Somersetshire, near Bristol ; Bath 

 and Cheddar Cliffs ; Gloucestershire, Painswick on walls ; Devonshire ; Cornwall. 



WALES.*. . . Caernarvonshire, in various localities ; at Cwm Idwel in profusion; Denbighshire, Dinas 

 Bran, near Llangollen, and near Wrexham ; Merionethshire near Maentwrog ; Mont- 

 gomeryshire, Craig Breidden and Cwm Istwith; Radnorshire, Craig-Pwll-du; Breck- 

 nockshire, Brecon; Carmarthenshire; Glamorganshire. 



SCOTLAND . . Throughout the Western Highlands, and in localities too numerous to mention. 



IRELAND.. . County Antrim, Red Bay, and Glenarriff; county Sligo, near Sligo in profusion; 

 county Galway, various localities in Cunnemara ; county Kerry, various localities. 



THE genus Cystopteris was established by Bernhardi, and 

 appears to have been adopted by nearly all subsequent botanists ; 

 it contains but a limited number of species, all of which frequent 

 moist or mountainous districts, rooting in the fissures of rocks, 

 or the interstices of stone walls. They are plants of small size, 

 of erect but elegant growth, and are of a remarkably brittle 

 character, whence the excellent specific name of fragilis. In this 

 country we have but one of these species, and on this much 

 labour, perseverance, and ingenuity have been expended, in the 

 hopes of exalting some of the more remarkable of its Protean 

 fronds to the dignity of species. So absorbing is this spirit 

 of species-making, that I believe nothing less than a month's 

 ramble in the Alpine districts of Caernarvonshire or Argyleshire 

 could possibly undeceive these who have thoroughly imbibed 

 a belief in the validity of these species ; and as those who are 

 strongest in the study are frequently the weakest on the moun- 

 tains, I doubt not that many will long cherish them with 

 unwavering faith. 



