THE TUNBRIDGE FILMY FERN 
389 
both the Filmy Ferns growing in great abundance upon the 
sides of a bill bordering a moorland stream, and covered by 
great masses of rock, amongst which there were trees and 
much other vegetation of a dwarfed or herbaceous kind. 
The situation w r as an extremely moist one, great mists occa- 
sionally rising from the river, and enveloping the hill-side. 
Clambering from rocky mass to rocky mass, we discovered 
that in numerous dark crevices formed by the overlapping 
edges of several rocks, the whole internal surface of stone 
was densely covered by a carpeting of Hymenophyllum, 
which was especially plentiful and luxuriant where trickling 
moisture oozed down from the higher hill-side along the 
internal surface of the rock. So dark were some of these 
rocky holes, that one could not look into their depths ; and 
sometimes in order to reach the spreading masses of 
Hymenophyllum, it was necessary to lie down along the 
top of the rock, and stretch out the hand at arm’s length. 
In many places, however, so moist was the entire atmo- 
sphere of the district, that the open tops and sides of great 
boulders were densely carpeted with Filmy Ferns, the thick 
masses of their rhizomas and rootlets having no depth of 
earth, but merely clinging to the damp surface of the 
boulders. 
Description. — The peculiar colour of the fronds of Hymen- 
ophyllum tunbridgense affords one mark of distinction, for 
it is a very dark olive green. In length they are from one 
to two or three inches, sometimes when very luxuriant being- 
found as long as six inches. Vast quantities of the plant 
will, however, be found not more than an inch or two inches 
in length. The stipes varies in length, sometimes being very 
short, and sometimes as long as the leafy portion of the 
frond, black in colour, and scarcely thicker than a hair. 
The rhizoma is about the same thickness, and it creeps ex- 
tensively amongst mossy and other roots, throwing up a 
