XVI HYMEXOPHTLLUM. 209 
rein lengthened out beyond the margin, and assuming a 
cylindrical or sub-clavate form ; and they are surrounded 
by an involucre of two nearly orbicular valves, spinnlosely 
serrate on the upper margin, and adpressed throughout the 
greater part of their length, but become slightly gibbous 
at the base, where the spore-cases are situate. The 
receptacle does not extend much beyond the middle of 
the valves. The plant is of an olive green colour, and is 
seen to be elegantly reticulated when slightly magnified. 
This little moss-like species is found widelv distributed 
in England, Wales, Scotland, and Ireland, growing amongst 
moss in mountainous situations, or on the surface of damp 
rocks and stones. It is also found in the alpine districts 
of Europe, in the Azores, Madeira, and the Mauri- 
tius, at tlio ( '.npe of Good Hope, in South America, Tas- 
mania, and Ntw Zealand. 
2. Hymenophyllum unilaterale, Willdenow. 
Wilson's Film Fern. Fronds rigid pinnate ; pinnae sub- 
secund recurved, four tosixlobed, the segments linear un- 
divided or bifid spinulose-serrate ; involucres solitary 
axillary ovate inflated entire ; rachis slightly margined. 
HTMENOPHYLLCM UMLATERALE, Willdenow: Newm. 14. - 
IlTMENOPHYLLUMWiuoM. Hooker, Brit. Fl. 446: Eng. Bot. Supp. 
2686: Newm. 325: Hook and Arn. Fl. 577: Bab. Man. 416: 
Florigr. Brit, iv., 124. 
Wilson's Film Fern resembles the Tunbridge species 
in its general features ; the texture of the frond in both 
is delicately membranous and pellucid, and when mag- 
nified even but slightly, is seen to be composed of closely 
arranged cells, which give it a beautifully reticulated ap- 
pearance, only in this the reticulations are somewhat 
larger. The caudex is filiform, creeping, and sparingly 
furnished with small brown pointed scales. The fronds 
are lateral, adherent, linear lanceolate, rigid, pinnate, 
from one to four inches high, or sometimes larger. The 
stipes is of variable length, as in the allied species, terete. 
p 
