Ferns of British India and Ceylon. 123 
(Also in West tropical Africa, the East African Islands, Queens- 
land, the Philippines, and Polynesia.) 
GENUS XXXII.— CERATOPTERIS. {Brong.) 
{XeraSj keratos, a horn ; pteris^ a fern: the horned fern.) 
Sori placed on two or three distantly anastomosing veins which run 
down the frond longitudinally, and are parallel both with the edge 
and midrib ; veins of the sterile fronds articulated in obHque oblong 
hexagonal areoles. Capsules scattered on the receptacles, sessile, 
subglobose, with a ring which is either compltte or more or less 
partial or obsolete. Indusium formed of the reflexed margin of the 
fronds, those of the two sides meeting against the midrib. A very 
anomalous genus, regarded by some as a distinct order ; it is very 
unlike Pterideae, and should be placed in a distinct tribe. 
I. Ceratopteris thalictroides. {Lin^ Stipes tufted, thick 
inflated, filled with large air-cells; fronds succulent in texture, the 
barren ones floating or erect, simple or slightly divided when young, 
bi-tripinnate with narrow hnear segments when mature, fertile ones 
bi-tripinnate ; ultimate segments podlike. Hook. Syn. Fil. p. 174. 
Bedd. F. S. I. t. 75. Acrostichum thalictroides, L. Sp. PI. 1527. 
Throughout India, Ceylon, and the Malay Peninsula up to 
3,000 feet elevation; common in tanks, ditches, and swampy places, 
or even dry ground during the rains. Mr. J. Smith says it is an 
annual, but I do not think it is so in cultivation, if kept in water 
or very moist, as I had the same plant growing for some years at 
Ootacamund. 
(Also in the tropics of the whole world.) 
