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112
THE MARINE ALGÆ OF NEW ENGLAND.
on different individuals, or when borne on the same individual not intermixed, but
on separate portions of the frond.
Common on stones near low-water mark.
Found in all parts of the world.
This common species abounds on rather smooth stones and pebbles, and when the tide falls covers
them with slimy films, which make walking over them difficult. The shape of the fronds is very
variable, but as generally found they are much folded and laciniate. The species is used for making
soups in Europe, but is not used in this country, except by the Chinese, who import it from China, not
knowing that it occurs abundantly on our own coast. P. leucosticta probably occurs in New England, but
has not yet certainly been observed. It is a spring species, softer and brighter colored than P. laciniata,
and the antheridia and spores are found on the same individual, forming spots within the margin
rather than a marginal zone.
BANGIA, Lyngb.
(Named in honor of Niels Hofmann Bang, of Copenhagen.)
Fronds gelatinous, simple, filamentous, cylindrical, densely tufted, composed below
of a single row of cells, which, by repeated vertical division, become densely cellular
above; antheridia and spores formed by transformation of the cells of the upper part
of the filaments.
A small genus, of which most of the species are marine, but some are found in fresh water. The species
are not well characterized, for the differences in the length of the filaments, color, and number of cells
seen in cross-section, marks upon which most writers have relied, depend to a great extent upon the
age of the plant and its place of growth.
B. FUSCO-PURPUREA, Lyngb.; Phyc. Brit, Pl. 96; Reinke, l. c.‚ Pls. 12, 13.
Filaments blackish purple, two to six inches long, clustered in dense masses,
lubricous; antheridia and spores usually on different individuals.On wharves and
rocks between tide-marks.
Rather common along the whole coast.
Easily recognized by the fine, soft, dark-purple filaments, which cover rocks and wood work in patches
of considerable size with a dense gelatinous fleece. Although found on wharves in sheltered localities, it
also occurs on rocks exposed to the waves.
ERYTHROTRICHIA, Aresch.
(From ερυθρος [erythros], red, and τριχιον [trichion], a small hair.)
Fronds rose-colored, simple, filamentous, composed of a single row of similar cells
placed end to end; cell contents discharged in a spherical mass, which forms a spore.
A small genus, whose principal representative, E. ceramicola, is by many writers placed in Bangia. As
we understand the genus, it differs from Bangia in that there are no antheridia or tetraspores, the
reproduction being accomplished by the discharge of the cell contents in a single mass or spore. If
Bangia ciliaris of the Nereis, which