Acrosiichum.'] 
Fibre iss. 
515 
/ 
to the base, contracted at the tip into a fertile linear spike 3-4 in. 
long. Veins fine, immersed ; the main ones erecto-patent, distinct 
more than halfway to the edge, the veinlets anastomosing in copious, 
hexagonal areoles. Hymenolepis ophioglossoides, Bojer, Hort. Maur. 
407. 
Mauritius and Seychelles, frequent in the mountain forests. Also Madagascar, 
Bourbon, Comoros, Tropical Asia, and Polynesia, not African. 
A. sacciscefolium , Thouars ; Hook, and Baker, Syn. Fil. 408, a plant of Tristan 
d’Acunba is said by Bojer, probably in error, to have been found in Mauritius 
amongst the Savannd mountain^. It is one of the simple-fronded free- veined species, 
with a wide-creeping rootstock, dark brown linear scales, an obtuse lanceolate sterile 
frond 5-6 in. long densely clothed on the under surface with lanceolate bright 
brown shortly ciliated scales, with a long scaly stipe and a narrower fertile frond 
with a longer stipe. 
27. PLATYCERIUM, Desv. 
Capsules stalked, splitting transversely, with an incomplete vertical 
ring. Sori forming large irregularly-shaped patches on the upper part 
of the fertile frond, without any involucre. — Fronds of two kinds, the 
barren ones short and rounded, the fertile ones dichotomously forked, 
with broad segments ; veins anastomosing copiously. Distrib. 
Warmer regions of the Old World, one also American. Species 7. 
1. P. alcicorne, Desv. ; Hook, and Baker, S yn. Fil. 425. Barren 
frond sessile, suborbicular, \-l ft. broad, with prominent veins radia- 
ting from the base. Fertile frond cuneate-deltoid, 1-2 feet long, 
coriaceous, clothed beneath with thin white tomentum, two or three 
times dichotomously forked, with obtuse lanceolate ultimate segments 
f-1 in. broad. Sori forming patches at the base of the ultimate seg- 
ments, extending from edge to edge. 
Mauritius and Seychelles, on old trunks in the forests. Also East Tropical 
Africa, Madagascar, Comoros, Australia, and Peru. 
28. OSMUFTDA, Linn. 
Capsules short-stalked, splitting vertically, furnished with a short 
broad horizontal ring about the middle, aggregated into leafless spikes 
or panicles. — Large compound ferns, with free veining, the fertile seg- 
ments usually terminal or central on leafy fronds. Distrib. Temperate 
zone and mountains of the tropics in both hemispheres. Species 7. 
1. O. r^galis, Linn.; Hook, and Baker, Syn. Fil. 427. Boot- 
stock erect. Stipes tufted, naked, 1-1J ft. long. Fronds bipinnate, 
membranous, glabrous, 2-4 feet long ; rachises naked. Pinnae oblong- 
lanceolate ; pinnules lanceolate, obtuse, 1-2 in. long. Veins distinct, 
erecto-patent, forked. Fertile segments forming a regular bipinnate 
terminal panicle about half a foot long. O. obtusifolia, Willd. j Bojer , 
Hort. Maur. 421. O. Hilsenbergii, Hook, and Grev. 
Mauritius, at the Mare aux Vacoas, etc. Cosmopolitan in temperate and warm 
temperate regions. 
2 b 2 
