459- : TETRANDRIA MONOGYNIA. Trapa. 
ple underneath ; from three to four inches broad, and nearly as long. 
— Petioles villous, lengthening with the age of the leaves, towards the. 
apex much smaller, this part contains many inflated vescicles, which 
render the whole plant very buoyant.— Stipules two pair, the superior 
ones simple, semi-lanceolate, and caducous, the inferior pair at first 
simple and filiform ; but becoming ramous by age, permanent.— Pe- 
duncles axillary, solitary, shorter than the petioles, one-flowered, in- 
curved until the blossoms begin to decay, after which they bend down 
under the surface of the water, where the fruit grows, and comes to 
maturity.— Flowers pure white, expanding above the surface of the 
water late in the afternoon .— Calyx four-leaved, in opposite pairs, . 
leaflets lanceolate, villous, one of the pairs permanent. — Corol con- . 
tr acted; petals four, contracted into a tube at the base by the firmness 
of the calyx, above much broader, and expanding ; margins much 
curled.— Nectary cup- -shaped, on the top of the germ, round the 
swelled base of the style, eight-grooved, with the margins minutely 
lacerate, and curled.— Filaments four, incurved. -Anthers oval, in- 
cumbent.—Germ inferior, obconical, two-celled, with one ovulum in 
each attached to the top of the partition.— Nut inferior, of a turbi- 
nate triangular shape, a hard ligneous texture, and a blackish- brown 
colour, armed with two, strong, straight, conic, barbed spines, from 
the upper angles ; elegantly embossed, one-celled, not opening, but 
2 having a perforation in the top for the Embryo to pass, which is 
guarded with a circle of stiff converging bristles from its margin, 
forming a conical roof over the aperture, ^ Seed single, conform fo 
the nut. — Integument single, of a slightly brown colour, thin, but 
rather wash, and adhering firmly to the perisperm. — Perisperm . 
conform to the seed, white, and of a firm cartilaginous texture. 
Embryo in the apex of the perisperm. | 
Obs. This is evidently a species perfectly distinct from natans, 
and bicornis. From the former it differs in having only two horns, 
and from the latter in the horns being straight, very sharp, and barbed. 
i * The nuts are sold in the markets when in season, their kernels be- 
ing much esteemed by the Hindoos. MEUM OL 
