BRITISH FERNS. 



S3 



the plant which can be considered specific : indeed so striking 

 were these characters to me, that I quite believed it a species 

 until I had obtained an intermediate series of forms. 



The next variety I consider to be the typical form of P. fragile, 

 as described by Linneus. 



Cystea fragilis, Smith. Fronds several 

 together, from four to ten or twelve inches 

 high, lanceolate, pointed, smooth, of a full 

 though bright green, doubly or almost 

 triply pinnate. Rachis brown or black- 

 ish, very brittle and juicy, occupying one- 

 third or nearly half of the length of the 

 whole, destitute of scales, except at its 

 very base. The pinnae are usually nearly 

 opposite, acute, and of a moderate length ; 

 the pinnulae mostly alternate, ovate, acute, 

 or pointed; their base always tapering 

 and decurrent; they are by no means 

 linear or oblong, nor is their margin wavy, 

 but copiously, deeply, and sharply toothed, 

 and their substance is firm ; the lower and 

 larger ones are deeply pinnatifid, their 

 lobes resembling the upper pinnulae. 

 Masses numerous and crowded, globular; 

 at first pale, but finally blackish and con- 

 fluent, covering the whole back of the 

 frond. Indusium white, flaccid, mem- 

 branous, concave, irregularly jagged and 

 torn, sometimes lengthened out into an 

 oblong point, but soon turned back and 

 obliterated, or forced off by the swelling, 

 shining thecae, which, in an early state, 

 are often quite black, though subsequently 

 browner. Eng. Flora, iv. 299. 



In this description a discrepancy occurs in the colour of the 

 thecae ; the colour of the masses, in an early state, is very incon- 

 stant, but generally blackish; the autumnal fronds, when in 

 cultivation, have smaller masses than the vernal, the masses also 

 are rarely confluent, the frond itself is more minutely divided. 



I now proceed to a plant of very remarkable character, and one 

 which at first sight would perplex many an able botanist; and 



