TRICHOMANES. 191 



it comes from two Greek words, meaning hair, and excess, 

 in reference to these projecting hair-like receptacles. 



Trichomanes radicans, Swartz. 



The Bristle Fern. (Plate XVI 1 1, fig. 1.) 



This very beautiful plant exists only in the immediate 

 neio-hbourhood of waterfalls, and in situations where a 

 constant moisture is maintained. Such conditions are, 

 indeed, quite necessary to it, on account of its semi-mem- 

 branous 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 

 pointed scales. The fronds are three or four times pinna- 

 tifid, cut up into small linear segments, which are entire or 

 bifid at the apex, and have a stout nerve or vein running 

 up their centre, and rendered very conspicuous in conse- 

 quence of the thin pellucid texture of the leafy expansions 

 which surround it. Or the frond may be described as con- 

 sisting 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 cellular membrane 



