FERNS OF THE MALAY- ASIATIC REGION. 
11 
5. Marattia ternatea de Vriese. (Plate VII.) 
Pinnules 10 to 20 cm long, 1.5 to 2.5 cm wide, abruptly narrowed at 
the base, margin obscurely serrate and usually deflexed, more sharply 
serrate at the apex, texture coriaceous; sori remote from the margin, 3 
mm long; sporangia about 15 pairs. 
Moluccas, Luzon. 
5. CHRISTENSENIA Maxon. ( Eaulfussia Bl.) 
Eliizome creeping, fleshy; fronds simple or palmate; veinlets anas- 
tomosing but without free included veinlets; sori irregularly scattered, 
round, the sporangia fused into synangia. Usually treated as a single 
species. 
Christensen ia aesculifolia (Bl.) Maxon. 
Stipe 20 to 45 cm high; leaflets 3 to 5, stalked or the lateral ones ses- 
sile, middle one the largest, 22 to 40 cm long. Eight to 12 cm broad; 
synangia of 10 to 15 sporangia. 
Malaya to northern India. 
Christensen ia cumingiana Christ Philip. Jouvn. Sci. Bot. 2 (1907) 186. 
(Plate VIII.) 
Stipe up to 17 cm high; frond most often simple, and up to 16 cm 
long and 10 cm wide, cordate, obtuse; sometimes with three leaflets, the 
middle one not over 15 cm long, sometimes whitish beneath. Sori of 7 
to 15 sporangia. Hardly distinct from C. aesculifolia. 
Mindanao, Negros, Luzon. 
HYDROPTERIDINEiE. 
Spores of two kinds in distinct sporangia: macrosporangia, each con- 
taining 1 macrospore in which the female prothallium develops ; and 
microsporangia, each containing numerous microspores which develop 
the male prothallia; sporangia borne in inclosed sori, close to the stem, 
on very reduced leaves or parts of leaves. Aquatic plants, very distinct 
in appearance from other ferns. 
3. MAESILEACEdE. 
Aquatics with stems creeping on the bottom and leaves which are 
without blade, or with blades floating on the surface or rising above it, 
eircinate in vernation (like the true ferns) ; macrospores and micro- 
spores borne in the same sori. 
Three genera — Pilularia, whose leaves are destitute of lamina, wanting in this 
part of the world; Regnellidium, with one Brazilian species; and the following: 
