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158
THE MARINE ALGÆ OF NEW ENGLAND.
small branchlets, which become swollen and usually have an opening on each side for the escape of the
spores. A longitudinal section shows an axile placenta which passes through the cystocarp, on which
the spores are borne, not in chains but singly. Numerous filaments connect the placenta with the wall
of the cystocarp. The account given above of the frond applies merely to what one sees in sections of the
mature branches. A section of the younger portions shows that there is originally an axile filament,
from which are given off other filaments which are nearly parallel to the axis, and which afterwards
turn outwards and form the cortical layer, the cells of which they are composed becoming rounder and
short. The genus differs from Pterocladia merely in the position of the placenta, which in the lastnamed
genus is not central, but is attached laterally to the wall of the cystocarp.
G. CRINALE, J. Ag., Epicr. (Gelidium corneum, var. crinale, auct.—Acrocarpus
lubricus and crinalis, Kütz., Tab. Phyc., Vol. XVII, Pls. 32, 33.)
Fronds cæspitose, dark purple, setaceous, one to three inches high, primary axis
procumbent, from which arise erect, subterete, once or twice pinnate branches,
pinnæ distichous, alternate, short, patent, acute, often pinnatifid; tetraspores
cruciate, borne in thickened subspathulate or pinnatifid apices.
Forming tufts on mud-covered rocks and stones at low-water mark.
Portland, Maine; Red Hook, N. Y., Harvey; New Haven; Wood’s Holl, W. G. F.;
Maiden, Mass., Mr. Collins; Europe; California.
We have followed Agardh in separating the var. crinale from the polymorphic and very widely diffused
G. corneum. The typical form of the latter occurs in Florida and on our west coast. G. crinale has been
as yet recorded in but few localities, but it is probably common along our whole coast. It is a homely,
insignificant species, usually not much thicker than a bristle, and forms small blackish patches on
mud-covered rocks.
SUBORDER SOLIERIEÆ.
Fronds filiform or compressed; tetraspores cruciate or zonate; cystocarps immersed
in the frond, usually prominent at one side, spores arranged in short filaments and
arranged in tufts around a large central carpogenic cell or a central placenta, which
is attached to the wall of cystocarp by filaments; carpostome distinct.
A small suborder, of which we have but a single species. It is characterized by having the spores
produced few in a row and attached either, as in Solieria and Eucheuma, to a large central cell, or, as in
Rhabdonia, to a large cellular placenta at the center of the cystocarp. Whether Rhabdonia should be
united in a suborder with Solieria is perhaps doubtful. By some the genus is considered to be related to
the Rhodymenieæ, and its affinity to Rhodophyllis and perhaps Euthora is not remote.
RHABDONIA, Harv.
(From ραβδος [rhabdos], a wand.)
Fronds deep red, cylindrical or nodose, branching, formed of an axis composed of
slender, branching, longitudinal filaments surrounded by