HYMENOPHYLLTJM. 113 



HYMENOPHYLLUM TUNBRIDGENSE, Smith. The Tun- 

 bridge Filmy Eern. (Plate- XY. fig. 2.) f^\ 



This is so named in consequence of its having been 

 found in the neighbourhood of Tunbridge, though occurring 

 also in many other parts of the United Kingdom. It grows 

 in the form of matted tufts, on the surface of damp rocks, 

 in the sheltered, humid localities which are congenial to 

 it; the black, wire-like, creeping stems being entangled 

 together, and interlaced with the mosses and allied plants 

 which are often found in its company. The fronds are very 

 short, from one to three or four inches long, membranous 

 and semitransparent, almost erect, and of a dull brownish- 

 green even when fresh, which gives them in some measure 

 the appearance of being dead. These fronds are lanceolate, 

 or somewhat ovate; they are pinnate, with the pinnae pin- 

 natifid or bipinnatifid, and having their branches mostly 

 produced on the upper side, though sometimes alternately 

 on each side the pinna. 



The fronds are virtually, as is the case with the TricJw- 

 manes, a branched series of rigid veins, winged throughout, 

 except on the lower part of the short stipes, by a narrow, 

 membranous, leafy margin. The clusters of spore-cases are 

 here produced around the axis of a vein, which is continued 



i 



