HYMENOPHYLLUM. 
195 
much propriety, from the membranous texture of their 
leaves or fronds. 
Hymenophyllum tunbridgense, Smith. 
The Tunbridge Film Fern. (Plate XV. fig. 2.) 
This is so named in consequence of its having been 
found in the neighbourhood of Tunbridge, though occur- 
ring 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 six 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 pinnatifid 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 Tricho- 
manesy a branched series of rigid veins, winged throughout, 
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