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REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 159
a layer of large roundish-angular cells and a cortical layer of smaller cells;
tetraspores zonate, scattered, immersed in the cortex; cystocarps immersed in the
frond, and projecting at one side, opening by a distinct carpostome, inclosing tufts of
spores arranged in short, dense filaments, surrounding a globose, cellular, central
placenta, connected by filamentous bands with a plexus of the axial filaments which
surrounds the sporiferous mass.
A genus comprising from fifteen to twenty species, the greater part of which are confined to Australia,
divided by Agardh into two subgenera, in one of which the frond is cylindrical and in the other
constricted at intervals. Our species belongs to the first division, and the frond resembles closely that of
Cystoclonium purpurascens, and the same is true of the tetraspores. The cystocarps are large, and
project on one side. The genus is placed by Agardh near Solieria, but in that genus the spores are
placed around a very large central carpogenic cell, while in Rhabdonia they are attached to a large,
solid, central placenta formed of cells. The placenta is attached to the walls of the cystocarp by
numerous bands of interwoven filaments, between which are the sporiferous masses, which consist at
maturity of short filaments, whose cells are changed into spores, which are not held together by a
gelatinous envelope as in Champia.
R. TENERA, Ag. (Gigartina tenera, J. Ag., Symb.—Solieria chordalis, Harv. (non Ag.),
Ner. Am. Bor., Part II, p. 121, Pl. 23 a.—Rhabdonia tenera, J. Ag., Spec.—R. Baileyi,
Harv. MSS., Am. Journ. Science, Vol, VI, p. 39.) Pl. XIV, Fig. 2.
Fronds deep red, from six inches to a foot and a half long, cylindrical, attached by a
small disk, simple below, above densely branched, alterantely decompound,
branches long, virgate, erect, tapering at the base and apex, and furnished with
numerous, linear, fusiform branchlets; tetraspores zonate, scattered in the cortex;
cystocarps numerous, immersed, but projecting at one side.
In warm, quiet bays, in shallow water.
Common from Cape Cod southward; Goose Cove, Gloucester, Mass., W. G. F.
A characteristic species of Long Island Sound, and only known in one locality north of Cape Cod, but
extending southward to the West Indies. It forms beautiful tufts often two feet long, in muddy places
around wharves and in sheltered places, and is not likely to be mistaken for any other plant, except
possibly for a large form of Cystoclonium purpurascens. The procarps consist of three cells, and from
the innermost or that nearest the axis grows a long trichogyne, which curves round in a tortuous
fashion, and makes .its way to the surface, reminding one of the trichogynes of Halymenia ligulata,
figured by Bornet. The section of the cystocarp given by Harvey in the Nereis does not pass through the
center, and the cystocarp is not a closed cavity, as supposed by Harvey, but has a distinct carpostome;
nor are the spores pyriform and attached to separate pedicels, but they are formed from the cells of
short filaments.