56 TlMEHRl. 
times larger than the latter, which, till removed, they quite 
conceal. 
i. Marsilea polycarpa, Hook and Grev., Baker, Jour. Bot.vol.24, 
p. 276. — Rootstock thick as small cord, free-creeping, naked, with filiform 
long descending roots, and scattered ascending petioles, that are slender, 
4-8 in. L, naked. Leaves 4-foliate, terminal on the summit of the 
petiole. Leaflets wedge-shaped, the outer edge rounded, at first folded 
together, spreading subsequently ; f-xj in. diameter each way, sessile, 
membranous, herbaceous. Venation reticulated, fine, with no primary 
ribs, anastomosing, forming^narrow elongated linear meshes. Sporangia 
subglobose li li. diameter, serial on the lower part of the stipes above 
a vacant space at the base, shortly stipitate, few or numerous, densely, 
tomentose, but becoming eventually naked. 
Common in estates trenches, and other still water, 
covering the surface densely, with oxalis, or clover-like 
foliage, and spreading over large areas. The local form 
is larger than usual. 
General distribution — From Cuba southward to Bra- 
sil. 
Order Hl-S&lvlnie. 
Annual aquatic floating herbaceous plants, of small or diminutive 
size, with imbricating or pinnatiform fronds and membranous major and 
minor capsules, which are situated in the axils of the leave beneath, or 
in inferior clusters on branched filiform threads, and that contain, 
separately, sporangia of two kinds. 
These are, in size, inconsiderable aquatic herbs, but they 
exist usually in great abundance, floating on the surface of 
still water, and are especially common in this country. 
The known species are about a score or more, which are 
spread through the torrid and the warm temperate regions 
of both hemispheres. 
Genus I.— Salvinia, Schreb. 
Small floating aquatic herbs, communal in habit, with serial fronds on 
a more or less shortly-extended rachis, entire, flat or partially folded 
