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REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 151
external, sessile or pedicellate, with a distinct carpostome, spores in several masses
composed of closely packed radiating filaments borne on a basal placenta.
A beautiful genus, comprising about twenty-five species, the most striking of which are found in
Australia, New Zealand, and at the Cape of Good Hope. P. coccineum is very widely diffused in the
North Atlantic and Pacific, and possibly also in the southern hemisphere; but it has only been observed
once on the coast of New England, and that perhaps requires verification. The genus is at once
recognized by the branching. The frond is linear and distichously pinnated, the pinnules, which are
always alternately secund in groups of from two to five, being of two kinds; the lowest pinna is short,
simple, and acute, while the remaining pinnæ are pinuulate or pectinate-decompound. The cystocarps
of Plocamium are similar to those of Rhodymenia, and the zonate tetraspores are in special branchlets
or leaflets, known as stichidia.
P. COCCINEUM, Lyngb.; Phyc. Brit., Pl. 44.
Fronds narrowly linear, without a midrib, decompound pinnate, pinnæ alternately
secund in threes or fours, the lowest subulate and entire, the upper pectinate on the
upper side; conceptacles marginal, solitary, sessile; tetraspores zonate on
divaricately branching processes borne on the inner side of the pectinated
branchlets.
Boston Bay, Miss Hawkshurst.
The above-named locality, given in the Nereis, is the only one known on the New England coast, for
this widely diffused species, if we except the vague statement of Bailey in the American Journal of
Science, Vol. Ill, 1847, p. 84, that it has been found by Rev J. L. Russell on the coast of Massachusetts.
One sometimes finds forms of Euthora cristata labelled P. coccineum in American herbaria. The
common Californian form of the species is coarser than the European, and has been named by Kützing
P. Californicum. It is not, however, distinct.
CORDYLECLADIA, J. Ag.
(From κορδυλη [kordyle], a club, and κλαδος [klados], a branch.)
Fronds filiform, irregularly branched, carnoso-cartilaginous, formed of two strata of
cells; medullary layer of oblong, longitudinal cells, cortical of roundish, colored,
subseriated, vertical, minute cells; conceptacles sessile on the branches,
subspherical, furnished with a cellular pericarp at length perforate, containing a
densely packed globular mass of roundish angular spores, formed by the evolution of
much-branched filaments issuing from a basal placenta; tetraspores immersed in the
periphery of pod-like ramuli, oblong, cruciately parted.
? C. HUNTII, Harv.
“Fronds densely tufted, springing from a common, expanded, crust-like disk, livid
purple, tereti-compressed, once or twice forked or secundly branched; branches
subulate, alternate, acute; fruit?” (Ner. Am. Bor., Part II, p. 155.)
Narragansett Bay, Mr. George Hunt.