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50
THE MARINE ALGÆ OF NEW ENGLAND.
still remains to be settled. The species does not adhere well to paper, and would probably, at first sight,
be referred by collectors to Chætomorpha rather than to Rhizoclonium.
CLADOPHORA, Kütz.
(From κλαδος [klados], a branch, and φορεω [phoreo], to bear.)
Filaments firm, not gelatinous, branching throughout.
A genus including the greater part of the branching Chlorosporeæ, which are found both in salt and
fresh water. It differs from Ulothrix and Chætomorpha in having branching filaments, and from
Rhizoclonium in having well-developed branches and not mere rhizoidal growths. The species abound
on rocks and in tide-pools, as well as in ditches and shallow bays along the shore, and usually grow in
tufts. Some of the species, however, especially those growing in brackish ditches, at maturity form
dense layers upon the surface of the water or on the bottom. The number of described species of the
genus is immense, but, in all probability, a great part are not distinct. It is at present impossible
correctly to refer the New England species to European forms, since European botanists by no means
agree as to their own species, and there has been a tendancy [sic] on the part of algologists of different
countries to ignore the species of other countries in studying their own. The principal specific character
is the mode of branching, which, in the present genus, is at best an uncertain mark. The young and old
plants of the same species often differ very much in the appearance of the branches, so that the habit
varies at different seasons. When old, some species are usually torn from their attachments and
washed ashore in large masses, and, in this battered condition, it is often impossible to recognize the
species, or perhaps even to distinguish the specimens from Rhizoclonium species. Unfortunately,
names have been given to the battered forms until there is such a labyrinth of synonyms that one is
tempted to reject all but a few well-marked species. In the present instance we have attempted merely
to compare our specimens with those in the Algæ Danmonienses, the Algues Marines du Finistère, the
Algæ Scandinavicæ of Areschoug, and with specimens received from Dr. Bornet, M. Le Jolis, Dr.
Kjellman, and Dr. Wittrock. It is to be hoped that some responsible algologist will undertake the
revision of this much-abused genus.
SUBGENUS SPONGOMORPHA, Kütz.
Plants spongy, at least towards the base, owing to the interlacing of the branches,
some of which are strongly recurved and rhizoidal.
C. ARCTA, (Dillw.). (Cladophora arcta, Phyc. Brit., Pl. 135.)
Filaments slender, two to eight inches long, tufted and densely matted at base,
becoming free and divergent above, color a bright green; branches near the base
strongly recurved and interlaced, upper branches erect or appressed, numerous,
opposite or scattered, apices obtuse; cells at base about twice as long as broad, cells
of upper portion several times longer than broad, average diameter of cells about
.08 mm .
On rocks between tide marks. Winter and spring.
Common along the whole coast; Europe.
One of the few species which are recognized without difficulty, although it varies considerably in aspect
at different seasons. When young the filaments are but slightly matted together, .except at the very
base, and the species is then the C. vaucheriæformis