Trichomanes. | XCIV. FILICES. 571 
localities in western Spain, South Wales, Yorkshire, Argyleshire, and 
Killarney in Ireland. Fr. summer. [T7. Andrewsti, Newm:, is a pretty 
form with a narrower frond, many-winged involucres, and larger 
receptacles, ] 
Soe a 
XVII. HYMENOPHYLLUM. FILMY FERN. 
Half-pellucid Ferns, closely resembling Z'richomanes, but usually 
smaller ; the involucres deeply divided into 2 lobes, and the bristle or 
receptacle usually concealed within them. 
A large genus, with nearly the same range as Z’richomanes. 
1. H. tunbridgense, Linn. (fig. 1314). Tunbridge F.—Rootstock 
very slender, creeping, and much branched with numerous fronds, 
forming broad, dense, almost moss-like patches. Fronds pinnate, 
seldom above 2 or 3 inches long, lanceolate in general outline; the 
stem very slender; the segments deeply divided into 3 or 8 or more 
oblong-linear lobes, which appear minutely toothed when seen through 
a lens. Involucres at the base of the segments or their lobes, on their 
inner edge, ovate, about a line long, deeply divided into 2 flattish lobes, 
often minutely toothed round the edge. 
In moist, rocky, or shady situations, dispersed over most of the 
warmer mountain districts of the Old World, especially in the southern 
hemisphere, more rare in America, extending from the Canary Islands 
and western Europe to Belgium and Norway, but not recorded from 
eastern Europe or any part of the Russian dominions, nor from North 
America. Generally distributed over the greater part of Britain, but 
more frequent in Scotland, northern and western England, and Ireland, 
than in eastern England. Fr. summer and autumn. A variety with the 
valves of the involucre entire, not toothed, is usually distinguished as 
a species, under the name of H. unilaterale, Willd. (fig. 1315), or A. 
Wilsoni, Hook., but the other characters, said to accompany this one, 
such as the narrow involucres, the different direction of the lobes of the 
fronds, &c., do not appear to me to be so constant as they are supposed 
to be; and the teeth of the valves, when present, are very variable. 
The entire-valved form is the most common in Scotland and Ireland, 
but the two are often intermixed. 
