34 
DASYCLADEiE. 
which completely encases the frond and conceals its filamentous structure. In Cymopo- 
lia, again, we have a still further advance in structure ; for, not to speak of its calcareous 
shells, every node of which the branching frond is composed may be compared to the 
whole frond of a Dasycladus or a JSTeomeris. Like them, it is a tubular axis whorled 
with ramelli ; but these latter are so closely placed together that the whorled character 
is not obvious, and the branch has the mammillated look of a Codium , if its calca- 
reous shell be removed ; or of a piece of honeycomb, if viewed with the shell still 
remaining. 
The spores are of large size, and are always formed within proper fruit-cells or spo- 
rangia, and, so far as I am aware, are destitute of vibratile cilia, and appear to be 
formed on a much more perfect type than ordinary zoospores. They have a tough, 
hyaline, membranous coat, and enclose a mass of dense, dark green or brown endo- 
chrome. In Polyphysa and Acetabularia the sporangia spring directly from the axial 
tube ; in Dasycladus , Neomeris , and Cymopolia they are found on the ramelli, and 
are either special cells, developed in the axils of the ordinary cells (as in Dasycladus ), 
or are formed by metamorphose of a division of the ramellus, as in Cymopolia. 
All the plants of this order, with the exception of Dasycladus , secrete carbonate of 
lime, but in very different proportions. In Polyphysa and Acetabularia the calcareous 
matter exists as a thin varnish to the surface of the stem ; but in Cymopolia it forms 
as complete a shelly envelope as it does in one of the calcareous polypes, and indeed a 
dead frond in this genus might readily be mistaken for the husk of a zoophyte : its 
honeycombed pores closely resembling polype-cells. 
All the species are natives of the warmer parts of the sea. Dasycladus and Aceta- 
bularia have representative species in the Mediterranean ; and the latter is found also 
in the tropical Pacific. Neomeris , which may probably yet be detected on the Floridan 
Keys, has species in the West Indies and Pacific Ocean. Cymopolia is found in the 
Carribean Sea, and also at the Canary Islands. Polyphysa was discovered by Dr. R. 
Brown at King George’s Sound, and has recently been found at Port Lincoln, Australia, 
by Mr. Wilhelmi ; and at Swan River, by Mr. George Clifton. 
I am very unwilling to multiply families, especially among plants of such low 
organization as the Chlorospermatous Algas, and yet I have been in a manner com- 
pelled to remove from the Siphonacece both the little group now described, and the 
following one (Valoniacece); from the impossibility of devising any diagnostic charac- 
ter which would include the whole. The true Siphonacece are typically known by being 
wholly formed of long, tubular branching cells. In the Dasycladece the axis only is 
of this character ; the rest of the frond consists, as in Conferva , of strings of short 
cylindrical cells ; and the spores are of a higher type than in Siphonacece. In Valo- 
niacece tubular branching cells are found, if at all, only in the root, or in a spongy caudex, 
while the principal part of the frond is formed of confervoid filaments. They approach 
Dasycladece through Chamcedoris , and possibly Kiitzing may be correct in associating 
them, as he has done in his latest arrangement, with this group ; but, ignorant as we 
are of their proper fructification, I have not ventured to adopt this course. The habit 
of the true Valoniacece is dissimilar, and in none of them do we find the ramelliferous 
internodes which characterise the present family. 
