THE BRISTLfi FfiRN 85 



and among the more ancient names Trickomanes alatum and 

 ILyinenopliylhim alatum occur. 



This very beautiful plant exists only in the immediate 

 neighbourhood _of waterfalls, and in situations where a con- 

 stant moisture is maintained. Such conditions are, indeed, 

 quite necessary to it, on account of its semi-membranou:3 

 texture, which shrinks before an arid atmosphere ; and hence 

 it can only be successfully cultivated when kept quite close, 

 and constantly wetted over-head. This species has a creeping, 

 wiry, black-looking stem, clothed with scales. The fronds 

 are three or four times pinnatifid, cut up into small linear 

 segments, which are entire or bifid at the apex, and have a 

 Btout nerve or vein running up their centre, and rendered 

 very conspicuous in consequence of the thin pellucid texture 

 of the leafy expansions which surround it. Or the frond 

 may be described as consisting of a series of three or four 

 times branched rigid veins, margined throughout by a thin, 

 pellucid, cellular expansion or wing, a greater or less number 

 of the apices of the veins becoming surrounded by the cel- 

 lular membrane in the form of an urn or vase, and within 

 them bearing the fructification. 



The fronds are pendulous, and vary from an angular- 

 ovate to a lanceolate form, the divisions being considerably 

 undulated, so that they acquire a crisped appearance. The 

 first series of lobes are usually of an ovate-lanceolate form ; 

 the next series shorter, more ovate, and the third series of 

 divisions narrow, more or less linear. The ultimate branches 

 of the veins which extend into the divisions of this third 

 series, end just at or within the apex of the lobes if they are 

 barren ; but if they are fertile, they are produced beyond 

 the margin, and surrounded at the base by the urn-shaped 

 involucre, within which the spore-cases are placed. Some- 

 times the involucre is so placed as to appear immersed within 

 the margin, but it more frequently projects. The length of 

 the bristle-like receptacle is variable. 



The variety Andrewsii is the lanceolate form of this plant, 

 in which the pinnae or first set of lobes are narrow and dis- 

 tinct. 



The Sister Isle now claims, so far as the British Isles ari 

 concerned, sole parentage of this lovely, half-transparent 

 species ; there, amidst dripping rocks, it thrives with a de- 

 gree of luxuriance which charms every one who lias seen it 

 creeping over their shelving ledges. It is said to have been 

 formerly found in Yorkshire. The same species is widely 

 distributed in the warmer parts of the world\ 



