dotted, or clothed with a tessellated membrane. A transverse section 
(fig. 4.), exhibits a narrow central tube, surrounded by several rows of 
hexagonal cells, each of which contains a coloured bag; a longitudinal sec- 
tion (fig. 5.), shows that the central tube is jointed at intervals of four to 
five times its breadth, and that the cells that encompass it become gradually 
shorter towards the circumference. The frwit (which I have not seen) con- 
sists of ceramidia, which have only been noticed by Roth, by whom they 
are very imperfectly described ; and stichidia, or lanceolate pods, terminating 
the branches, and containing triparted tetraspores, Colour purplish, 
brownish or greenish, according to locality. Sudstance cartilaginous, im- 
perfectly adhering to paper in drying. 
In the year 1838, Dr. Montagne, m the botanical portion of 
M. de la Sagra’s history of Cuba, established his genus Bostry- 
chia upon B. scorpioides, and a tropical species, B. calamistrata, 
with which he has since associated several others, having similar 
organization ; and I wish now to extend the generic character, 
so as to comprise a little group of southern species, to which I 
have elsewhere applied the name Stictosiphonia, which differ 
from the type, in having thei central tube surrounded by a 
single row of coloured cells. The genus thus constituted con- 
sists of ten species, all of which have a similar habit, and all are 
found in situations either bordermg on high-water mark, or in 
places where a considerable quantity of fresh water flows into 
the sea. In this respect they differ from most other Rhodo- 
melee, a tribe of Algee the majority of which grow at a consi- 
derable depth, and are peculiarly impatient of the contact of 
fresh water. So little is this the case with our B. scorpioides 
that it has been called amphibia, from its sometimes growing in 
ditches of brackish water, and such also, according to Dr. 
Hooker, are the situations chosen by B.vaga, at Kerguelen’s 
Land. 
The name //elicothamnion, proposed by Kiitzing for B. scor- 
proides, must be laid aside, as that of Bostrychia has the priority, 
is equally applicable, and more euphonious. By Prof. J. Agardh 
this group is included in A/sidium, but it scarcely agrees with the 
character of that genus, and still less with the habits of its species. 
Fig. 1. Bosrrycu1a scorpiorpEs, a tuft :—of the natural size. 2. Part of a 
branch. 3. Involute apex of the rami, with a portion of a lateral branchlet. 
4. Transverse section of a branch. 5. Longitudinal section of the same : 
—all more or less highly magnified. 
