BRITISH FERNS. 



33 



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 fra^Uis, 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 pinnulge 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 pinnulge. 

 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 ofl* by the swelHng, 

 shining thecae, which, in an early state, 

 are often quite blach, 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 



