76 
SPOROCHNACEiE. — Desmarestia. 
iv. 
vertically, the innermost of wliich are of largest size, and the cells of each row to 
the circumference of less and less dimensions. The substance of the frond when 
quite fresh is cartilaginous, but it soon becomes flaccid in the air ; and the colour, 
which at first is a bright bay, rapidly changes to verdigris green. The fructification 
is borne on the lowermost divisions of the whorled filaments, and forms moniliform 
strings of spores springing from the inner faces of the branch. These are deve- 
loped by the metamorphosis of secuncl ramuli, and consist of a large number of 
very minute, oblate spores, which fall asunder when mature. In drying, the plant 
adheres firmly to paper. 
I am indebted to Mr. Congdon for one of the few specimens of this rare plant, 
which he succeeded in saving during a very hasty visit to the shore near the 
mouth of the Cape Fear River. It is roughly dried, and I have, therefore, been 
obliged to use more carefully preserved (British) specimens to give an idea of the 
natural appearance of the species (at PI. IV. fig. A 1 .), but I have drawn the mag- 
nified figures (2, 3, 4, 5, 6) from Mr. Congdon’s specimen, so that there can be no 
doubt of their identity. The description of the species given above is mostly 
copied from the Phycologia Britannica. The magnified figures in PL 64 of that 
work, especially figs. 2 and 4, are much less correct than the corresponding one 
(2 and 5) now given. 
II. DESMARESTIA, Lamouroux. 
Frond linear, either cylindrical, compressed or flat, pinnated, solid, traversed by 
a slender articulated filament (or axis) ; the solid parts composed of several rows 
of small cells. Branches when young producing along the margin, and from the tips, 
tufts of byssoid, articulated, repeatedly pinnate filaments. Fructification unknown. 
This genus, of which the fruit is at present unknown, is readily distinguished 
from Artliroclaclia , by the structure of the frond. Here there are not the knots 
along the stem and branches, whorled with delicate filaments, which mark that 
genus ; and moreover the frond, in the present group, is destitute of a tubular 
axis of large calibre. It is true that the articulated filament which traverses the 
stem and branches in Desmarestia may be compared with the articulated tube of 
Arthrocladia , but the former consists of a string of single cells, placed end to end ; 
the latter is a compound structure, whose walls and septa are both made up of a 
great number of cells. 
The manner in which the frond is developed may be readily seen by examining, 
under the microscope, any tip of a young branch in process of formation ; par- 
ticularly in the young points of D. viridis and I). ligulata , in which species the 
frond is more transparent than in D. aculeata. In I), viridis the young branch is 
prolonged, at its apex, into a confervoid filament, formed of a row of cylindrical 
