184 
BRITISH FERNS. 
and their full stature is not perfected till the second 
year ; the third year is their harvest-time. 
In order to grow this fern in the greenhouse Mr. 
Johnson directs that a pot be filled one-third with broken 
crocks and sandstone rubbish, and the remainder with 
equal parts of fine loam, silver- sand, and powdered sand - 
stone ; the roots then to be laid on the surface, and fixed 
with pegs, then a little sand strewed over, just enough 
to cover the roots, the whole watered liberally from a 
pot with a fine rose, and plunged in a saucer full of 
water, a bell glass being turned over, its rim resting in 
the saucer. 
This fern is abundant in the south of Europe, and in 
various parts of Asia, North and South America, the 
West Indian and Sandwich Islands. 
H Y MEN OPH YLLUM. 
Gen . Char. Involucre two-valved. Sori sessile, with a broad 
ring. 
43. Hymenophyllum Tunbridgense. Tunbridge 
Filmy-fern. 
Caudex thread-like, creeping. Stems winged. Fronds tender, 
pinnate. Leaflets narrow, toothed. Involucre urn-shaped and 
sharply toothed. 
The Filmy-ferns are moss-like plants ; the name is 
derived from two Greek words — hymen, membrane, and 
phyllon , leaf. 
The Tunbridge Filmy-fern has slender thread-shaped 
roots proceeding alone, or in twos or threes, from a 
brown caudex, nearly as slender as themselves. The 
fronds are formed of branching veins, winged with ver- 
