order, Aponogetacee, and that Ouvirandra should rank with it. 
Perhaps, indeed, Du Petit-Thouars was led more especially to 
constitute a new genus of this in consequence of the remarkable 
organization of the foliage: but, curious and general as is the 
fenestrate character in the present species (and probably in the 
O. Heudelotii, Kth.) from Senegambia, briefly noticed by De- 
caisne, /.c.; yet, in the O. fenestralis, we find occasionally a leaf 
(as in the annexed figure) wholly or partially entire, that is, 
having the areole of the nerves filled up with parenchyma: and 
Decaisne has described and figured a second species of Ouviran- 
dra, of Madagascar (O. Bernieriana), filled up with parenchyma, 
« foliis plenis,’ exactly as in any ordinary Aponogeton. Our 
flowering plant produced no seeds. 
Descr. Mr. Ellis has in the above account described so much 
of this plant, that but little remains for us to notice. The root 
with us has not shown “tubercles,” but consists of a horizontal, 
branching cavdex or rhizome, emitting numerous descending 
fibres from below ; and above, from different points, clusters or 
fascicles of long-petiolated /eaves, which spread more or less hori- 
zontally beneath the surface of the water ; they are oblong-obtuse 
at the apex, with a mucro, and more or less obtuse at the base : 
this blade of the leaf has a strong midrib; the rest is wholly 
formed, and from the earliest stage of development, of what ap- 
pear to be longitudinal nerves meeting at the point, and con- 
nected by transverse nerves or nervelets, of a pale yellowish- 
green colour when young, brighter and deeper green when fully 
formed, and becoming dark olive-green in age. If these nerves 
and nervelets are seen under a microscope, they will be found 
to consist of very slender nerves surrounded by a portion of 
parenchyma* on each side; sometimes the parenchyma is ex- 
- tended, so that the open portion is of an oval form, and in some 
rare instances, as above observed, an entire leaf is formed of 
parenchyma traversed by the slender nerves. The petioles vary 
in length from a finger’s length to a span long, and are terete, 
slightly sheathing at the base. Seape from the midst of the 
petioles, exactly resembling the petiole, and probably varying in 
length according to the depth of water, for the flower-spikes 
attain to the surface of the water. Before the spzkes, two in 
number, are developed, the dilated apex of the scape bears a 
small, calyptriform, striated, deciduous lid,t which falls off en- 
* The cells of the parenchyma are very delicate, full of fluid and granules of 
green chlorophyll. The nerve consists of a few long, green, tubular cells, sur- 
rounding several very slender spiral tracheze in the main ribs, but a single onein 
the nervelets. There are’no air-cells in the substance of the leaf, or in the apex 
of the petiole. —J. D. H. : 
+ Mr. Ellis called my attention to this, and made a sketch of it, sending me 
the fallen lid; for it had fallen before the plant arrived at Kew. 
