a new genus of Pontederiaceae. 93 
of repeated dissections by myself of all the organs. Mr. Clarke 
describes the embryo as occasionally doubled on itself in a 
slight degree at the extremity most remote from the hilum, 
a character I have not found in the numerous seeds examined. 
He was at first disposed to refer the plant to Podostomaceae, 
but subsequently to regard it as a near ally of Halophila . The 
position of the plumule was ascertained by Mr. Clarke, and 
verified for me by Mr. W. Fawcett, F.L.S. 
It remains to offer a few notes on the anatomy of this 
singular plant, which in the matter of the morphology and 
histology of its organs requires a more complete investiga- 
tion. The stem is cylindric and terete, invested by one layer 
of epidermal cells with a thickish cuticle, and the epidermis is 
traversed by long red resin-canals. Beneath the epidermis are 
two or three layers of very large thin- walled cells of the cortex, 
which give off vertical rays enclosing air-spaces to the similar 
cells surrounding the central axis. The latter is very in- 
distinctly vascular, and has a few thick-walled cells in its peri- 
phery. Very feebly developed isolated vascular bundles also 
occur at the outer extremities of the cellular rays. Dr. Balfour, 
who has kindly prepared sections showing these tissues for 
me, informs me that this very simple structure is what occurs 
in many Naiads, Hydrocharids and other water-plants, and that 
reservoirs of a similar red resin are found in Eichhornia , also 
a Pontederiad. The leaves, which are slightly compressed 
from back to front, present similar tissues to the stem, 
including the long resin-canals. In the delicate membrane 
of the spatha I find no resin-canals, but bundles of cystoliths ; 
the latter occur also in the bracts, together with short 
scattered resin-canals. In the corolla still shorter resin- 
canals are seen. Spiral vessels are most readily detected in 
the bases of the leaves and in the placental tissue. 
The Camp, Sunningdale. 
