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REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 169
R. SUBFUSCA, Ag.; Phyc. Brit., Pl. 264.
Exs.—Alg. Am. Bor., Farlow, Anderson & Eaton, No. 55.
Fronds six inches to a foot and a half long, terete, pinnately decompound, branches
virgate, lower branchlets patent, subulate, the upper fasciculato-corymbose;
tetraspores prominent in subtorulose branchlets; cystocarps sessile, ovato-globose.
Var. GRACILIOR, J. Ag. (Rhodomela gracilis, Harv., Ner. Am. Bor.‚ Part II, Pl. 13 c.)
Fronds slender; tetrasporic branches distinctly torulose.
In deep tide-pools and at a depth of several fathoms.
Throughout our whole limits; Europe.
A species which varies very much with the time of year and the place of growth. It is. usually common
in the spring months, when it is often washed ashore, and in the summer and autumn it is occasionally
found, especially in dredging, in a denuded form, nothing remaining but the older branches, which are
perennial and which give rise the following season to rather delicate new branches. As usually seen on
Cape Ann the fronds are short, robust, and dark colored, even in early spring, while at Wood’s Holl and
in Long Island Sound the common spring form is much attenuated, delicate, and of a brighter red color,
forming the Rhodomela Rochei of the Nereis. In spite of the difference in aspect, the extreme forms are
connected by numerous transitional stages which make it impossible to admit a specific distinction. By
Agardh R. Rochei is considered to be the spring form of the typical R. subfusca, but we are more
inclined to regard it as the young of the var. gracilior, which is more common south of Cape Cod, the
type occurring northward. The species does not adhere well to paper.
POLYSIPHONIA, Grev.
(From πολυς [polus, many, and σιφων [siphon], a tube.)
Fronds filamentous or subcompressed, distichously or irregularly branching, formed
of a monosiphonous axis and several (4-20) siphons, often with secondary siphons,
and either naked or with a cortical layer of irregular cells, furnished with numerous
tufts of hyaline, monosiphonous, dichotomous filaments; antheridia lanceolate in
outline, borne on the dichotomous filaments; tetraspores tripartite, in one, rarely in
two, rows, in the slightly altered upper branches; cystocarps ovato-globose or
urceolate; spores pyriform, on short pedicels borne around a basal carpogenic cell.
The largest genus of Florideæ, of which more than two hundred species have been described, but not all
of which can be considered valid. They abound in all parts of the world, especially in warm, shallow
waters. Some are perennial, but the majority are annual and disappear during the winter. They are
easily recognized at sight by the structure of the frond and the tetraspores, which are almost always in
a single row in the upper branches, rarely in a double row, and not in swollen special branches or
stichidia, as in Bostrychia, which is nearly related to Polysiphonia. The growth is from a single apical
cell, from which is formed a monosiphonous axis. By tangential divisions of the upper cells there is
formed a number of peripheral cells and a central