288 



BBISTLE FEKN, 



smaller plants, possessing more radicle and less rhizome, and 

 having the radicles fixed in a thin la,yer of moist earth, among 

 a profusion of moss and Hymenophyllum. The young frond 

 exhibits itself in a very rudimentary state in the autumn, and 

 at any part of the rhizome except its growing extremity ; its 

 full development is not complete until the November of the 

 following year, and it takes another year to produce the seed- 

 vessels ; the fronds usually endure for many j^ears. The to- 

 mentose covermg of the rhizome is found, under a lens of high 



power, to consist of articulated bris- 

 tles, which are evidently analogous to 

 the scales on the stipes of other ferns : 

 they may be seen most abundantly 

 on the young frond, before it has un- 

 rolled, and may be found scattered 

 here and there on the stipes after the 

 frond has attained maturity : they 

 are of a rich brown colour, the di- 

 lated portions being slightly transpa- 

 rent. I have attempted to show the 

 structure of these bristles in the mar- 

 ginal figure. Intermixed with these bristles are others much 

 finer, much shorter, and more transjDarent ; and these, under a 

 lens of sufiicient power, are also found to exhibit traces of arti- 

 culation : the tomentose appearance of the radicles is due to 

 these minute bristles. The form of the fronds is between lan- 

 ceolate and triangular, those from Glouin Caragh approaching 

 the former, those from Killarney the latter form : they are pin- 

 nate, the pinnae being alternate and pinnate, and the pinnules 

 deeply divided or pinnatifid : perhaps it would be more correct 

 to describe the hard, woody, wu-e-like veins as thus divided, and 

 to say that each of these veins is furnished on each side with a 

 semi-membranous wing extending throughout its length : the 

 entire frond is composed of these wings, and consequently all 

 its divisions are narrow and linear : this wing extends also to 

 the stipes, which is about equal to half the frond in length. 

 The fructification may be thus described : — the cluster of cap- 

 sules is small, and nearly spherical, and is attached all round 

 the vein after its ultimate division ; at the point of attach- 

 ment the wing partially loses its green and semi-membranous 



