BRITISH FERNS. 17 



ROCK BRAKES. 



ALLOSORUSCRISPUS. Bernhardi, Sprengel, Sadler, Presl. 

 Osmunda Crispa. Linneus, Hudson, Lightfoot, Bolton, Berken- 



hout. 



Onoclea Crispa. Roth. 

 Phorobolus Crispus. Desveux. 



Cryptogramma Crispa. Brown, Hooker, Mackay, Francis. 

 Pteris Crispa. Smith, Withering. 

 Stegania Onocleoides. Gray. 



LOCALITIES. 



ENGLAND . . . Abundant on the mountains and about the lakes of Cumberland and Westmoreland ; 

 more sparingly on the mountains of Yorkshire and Lancashire. 



WALES Abundant on the mountains of Caernarvonshire; sparingly on Cader Idris; on 



Plinlymmon; on walls near Llyn Tregarien, Dolgelly, Tan-y-Bwlch, Aberglaslyn, 

 Beddgelert, and Llanberris. 



SCOTLAND . . . Mountains of Aberdeenshire, Argyleshire, Perthshire, &c. but not abundantly. 



IRELAND .... Mourne Mountains, county Down ; Liberties of Carrickfergus, county Antrim. 



FOR separating this species generically from the three follow- 

 ing, I am unable to assign any better reason than that every 

 author has considered it distinct; it has by three eminent 

 botanists been made the type of a new genus ; viz. by Bern- 

 hardi, under the name Allosorus ; by Desveux, under the name 

 Phorobolus ; and by Brown, under the name Cryptogramma. 

 The name I have adopted has the claim of priority. The only 

 characters distinguishing this plant from our British Polypodia 

 are, that the fronds are both fertile and barren, and that the 

 margin of the fertile pinnula is reflexed, covering the masses of 

 thecae. In a few species, nearly allied to A. crispus, the masses 

 of thecae are linear. 



The root is fibrous, the fibres very numerous and tough, and 

 tenaciously adhering to the earth or stones : the rhizoma is dark 

 brown, and extends itself horizontally, but very slowly ; and the 

 plant, without a careful examination, appears to be tufted. 



c 



