176 HISTORY OF BRITISH PERNS. 



This very beautiful plant exists only in the immediate 

 neighbourhood of waterfalls,, and in situations where a con- 

 stant moisture is maintained. This is, indeed, quite neces- 

 sary to it, on account of its semi-membranous 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 

 stem, smallish, wiry, and black-looking, clothed with 

 pointed 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 stout 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 cellular 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 ; 



