138 FERNS. 
of forests, but always in the shelter of rocks, namely Grammitis 
rutifolia; this dwarf and downy Fern has its fronds divided some- 
what in the manner of the foliage of the Rue ; hence the name. 
The genus obtained its appellation from the usually linear fruit- 
masses. The other species Grammitis leptophylia is the smallest 
and most delicate of all our Polypodiacez, and it is further remark- 
able among them for its transparent tender-membranous fronds. 
It is of very sparse occurrence, for which scarcity its merely 
annual duration, so unusual in Fern, seems to account. The 
pellucidity of this little Fern, so exceptional among Polypodiacee, 
is almost universal among Hymenophyllee ; thus the latter are 
great favorites in the collections of dried Ferns, though their 
cultivation is beset with difficulties. We possess of this tribe two 
species of Trichomanes and two of Hymenophyllum ; they delight 
to grow on Fern-stems or on mossy rocks along rivulets in deep 
shady ravines exposed to the spray of cataracts or bathed in dew, 
and they beset often the Fern-stems so densely, as if they were 
clothed in the most beautiful shining green silk. Hymenophyllum 
Tunbridgense differs in the minutely serrated fronds from Hyme- 
nophyllum demissum. One of the Trichomanes is here and indeed 
anywhere in Australia of extreme rarity, namely Trichomanes 
pyxidiferum ; it is here a smaller plant than the following, more 
compound-pinnate, whereas Trichomanes venosum, a frequent plant 
on Ferntrees, has the segments of the fronds more confluent and 
veined. The transparent foliage of the Hymenophyllums suggested 
the generic name; that of Trichomanes is of remote antiquity, 
applied by Theophrastos, Dioscorides and Plinius to the also here 
occurring Asplenium trichomanes, which was used as a remedy 
against loss of hair ; the modern Trichomanes alludes to the hair- 
like fruit-axis. 
Passing to the Gleicheniaceze we have to deal with three 
Gleichenias, all confined to springy valleys, where Gleichenia 
circinnata will sometimes form dense masses of wide extent. 
Its ramification is doubly or repeatedly forked (dichotomous), 
and the ultimate pinne consists of numerous minute roundish 
segments. From this curious Fern can be distinguished Gleichenia 
dicarpa ouly by the lobes of the pinnz so much recurved as to 
