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162
THE MARINE ALGÆ OF NEW ENGLAND.
On wharves, shells, stones, and sponges below low-water mark, and extending to
several fathoms.
Cape Cod, southward.
This, with the exception perhaps of Dasya elegans, is the most beautiful alga of Long Island Sound. It is
often found in tufts on wharves below low-water mark, and it flourishes in rather warm, shallow bays.
It is met with at all seasons of the year; and, according to Miss Fisher, of Edgartown, the ladies of
Martha’s Vineyard collect it in winter, when it is found in considerable quantities on the ice. The male
plant is smaller than the cystocarpic, and the antheridia may be detected by the naked eye in the form
of small, whitish, glistening spots. The walls of the conceptacles are thinner than those of Delesseria.
The swellings in which the tetraspores are borne can hardly be called warts, and the figure given by
Harvey in the Nereis is somewhat exaggerated. The surface of the frond is raised, and becomes more or
less convex, but there are no such irregular projections as represented in Harvey’s figure.
DELESSERIA, Lam.x.
(In honor of Baron Benjamin Delessert.)
Fronds bright red, thin, membranaceous, laciniate or branched, coatate, and often
with lateral veins, composed of a single or a few layers of large polygonal cells;
antheridia in spots on the frond; tetraspores tripartite, grouped in spots (sori) on the
frond or on marginal leaflets; cystocarps external, sessile, with a basal placenta,
from which radiate the numerous subdichotomous, sporiferous filaments.
A beautiful genus, comprising fifty or more species, distributed all over the globe. They are of delicate
texture and rosy-red color, and are generally leaf-like in appearance, although some are narrowly
linear. The genus is not likely to be mistaken for any other on our coast, unless it be Grinnellia, in
which the tetraspores are borne in thickened portions of the frond. The fronds, when young, are more or
less leaf-like and provided with a midrib, and generally also with lateral nerves; and, as they grow
older, they become more or less stipitate by the wearing away of the blade of the leaf, which leaves the
thickened midrib either naked or with a small winged margin. When still more advanced, owing to the
growth of the laciniæ and the wearing away of the lateral nerves, the stipes appear to branch and to
bear several leaf-like fronds. In some, species the membranous portion of the fronds consists of a single
layer of cells, which are rectangular when seen in section and polygonal seen from above. At the veins
the cells form several layers, and in some species it is only at the tip that the fronds are formed of a
single layer. When the cystocarps are formed, the cells are divided by numerous partitions parallel to
the surface of the frond, and the wall of the conceptacle, when mature, consists of several layers of cells,
all of about the same size and smaller than the cells of the frond.
D. SINUOSA, Lam.x.; Phyc. Brit., Pl. 259.
Fronds four to eight inches long and two to four broad, stipitate below, stipe often
elongated and branched, with oblong or obovate, deeply sinuate or pinnatifid toothed
leaves, midrib percurrent, lateral veins opposite, extending to the laciniæ;
tetraspores tripartite, either borne in small lateral leaflets or in patches following
the veins; cystocarps sessile, generally on the veins, hemispherical, with a distinct
carpostome.
On algæ, generally in deep water.