HYMENOPHYLLTTM. 195 



mucli propriety, from the membranous texture of their 

 leaves or fronds. 



Hymenophyllum tunbridgense, Smith. 



The Timhridge 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 pinnge 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- 

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



2 



