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78
THE MARINE ALGÆ OF NEW ENGLAND.
A genus comprising eight described species, several of which are undoubtedly merely forms of the
common and widely diffused C. verticillatus, whose structure is minutely described by Pringsheim, l. c.
The term leaves is applied by Pringsheim to the secondary branches. He considers the branching of the
axis to be monopodial. The sporangia are produced in the winter months, the two kinds on separate
plants or sometimes together.
C. VERTICILLATUS, Ag.; Phyc. Brit., Pl. 33; Pringsheim, l. c., Pls. 1-7.
Fronds four to ten inches high, slender, subdichotomous, secondary branches
distinctly whorled, falcate, acute at apex, attenuate at base, furnished externally
with a few spine-like branchlets; hairs numerous; unilocular sporangia globose,
plurilocular sporangia irregularly ellipsoidal, borne on short pedicels on small
special branches, which grow front the axis between the insertions of the secondary
branches.
Var. SPONGIOSUS. (Cladostephus spongiosus, Ag.; Phyc. Brit., Pl. 38.)
Fronds more compact, whorls approximate, indistinct, secondary branches usually
destitute of hairs and spine-like branchlets.
On stones in pools and below low-water mark.
Newport, R. I.; Orient, L. I.; Martha’s Vineyard; Cape Ann, Mass.; Europe.
A plant at once recognized by its resemblance to a small Ceratophyllum. Rather common in several
places south of Cape Cod, but seldom seen on the northern coast. It prefers somewhat exposed shores,
and occurs at considerable depths. Although the close resemblance between C. verticillatus and C.
spongiosus has long been noticed, the two species have generally been considered distinct. Geyler says
that C. spongiosus is characterized by the absence of hairs and the external spines on the branches.
Although this is in general true, one not unfrequently finds hairs and small spines on some of the
branches, and C. spongiosus is evidently merely a variety of C. verticillatus. Nor is it the case, as some
have supposed, that the verticillate form is confined to deeper water, while the spongiose form is found
in tide-pools and near low-water mark.
FAMILY MYRIONEMEÆ.
Fronds minute, forming spots or thin expansions on other algæ, consisting of
prostrate filaments united into a horizontal membrane, from which rise short
vertical filaments, between which are borne the sporangia; unilocular and
pluriocular [sic] sporangia as in Ectocarpeæ.
MYRIONEMA, Grev.
(From µυριος [myrios], numberless, and νυµα [nyma], a thread.)
Fronds olive-brown, forming thin expansions on other algæ, composed of a horizontal
layer of cells lying on the substratum, from which arise very numerous vertical
filaments, closely packed together; unilocular and plurilocular sporangia between
the vertical filaments, either sessile on the horizontal layer or on short pedicels;
hairs arising from horizontal layer; growth peripheral.