39 ° 
THE FERN WORLD 
little forest of crowded fronds. So thickly do the rhizoinas, 
with their tinier fibrous, wiry rootlets, grow together, that they 
often form masses several yards square on the surface of a 
wide rock, and the masses are frequently so compact that they 
can be stripped off in sheets, for they hold together almost 
as firmly as the interwoven mass of a door-mat. The frond 
is ovate in form, and may be described as a series of 
branched, very tiny, but rigid black veins, margined 
throughout by thin, pellucid, semi-transparent leafy expan- 
sions or wings. The veins branch alternately from the 
waved racliis or mid-vein of the frond on each side of the 
rachis, the branches or pinnae being again divided into 
oblong, blunt-pointed pinnules, which are generally arranged 
in pairs on each side of the mid-veins of the pinnae. The 
appearance of these branched pinnae is not unlike the 
branching of some threads of coral. On closely examining 
the margins of the pinnules, or winged expansions, it will be 
discovered that they are spinulose, or very sharply toothed 
with bristling points. The frond is broadest in the centre, 
and tapers towards the base, and bluntly towards the apex, 
in each case by the gradual shortening of the pinna?. The 
arrangement of the fructification in this Fern is extremely 
interesting and beautiful. The spore cases are borne not in 
little heaps fit the backs of the fronds, but they are con- 
tained in little urn or cup-shaped receptacles or indusia, 
which are hoisted, so to speak, on the apices of the veins, 
which branch out of the mid-stems of the pinna? next and 
on each side of the main rachis. The veins bearing the cup- 
shaped indusia (which are indented on their upper margins) 
are very short — so short, that to the naked eye the urn- 
shaped indusia appear to be seated almost on the mid-stems 
of the pinnae. The veins which, branching from the latter, 
bear the cup-shaped indusia, enter at the ' base of and pro- 
ject into the cup, and around those parts of them which are 
