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REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 179
obliquely out wards to form the cortical layer. The increase in the length of the frond arises from the
elongation of the central bundle of filaments. The whole plant is covered by a dense cuticle. The
conceptacles are formed from the terminal cells of the filaments just mentioned, which cease elongating
and lose their calcareous incrustation, the cuticle also falling away. The peripheral filaments, at the
same time, continue to elongate and project beyond the central bundle of filaments, thus forming the
wall of the conceptacle.
C. OFFICINALIS, L.; Phyc. Brit., Pl. 222.—Common Coralline.
Diœcious, fronds two to six inches high, arising in dense tufts from a calcareous
disk, decompound-pinnate, lower articulations cylindrical, twice as long as broad,
upper articulations obconical or pyriform, slightly compressed, edges obtuse;
conceptacles ovate, borne on the ends of the branches, or some of them
hemispherical and sessile on the articulations.
Var. PROFUNDA, Farlow.
Fronds elongated, with few, irregular branches.
Common in tide-pools; the variety in deep water.
Europe; North Pacific?
The only species known on our coast, often lining the bottoms of pools, and when exposed to the sun
becoming white and bleached. C. squamata, which is monœcious, and has a filamentous base, and
whose upper articulations are compressed with sharp edges, especially on the upper side, is a common
species of Northern Europe, and may be expected with us.
MELOBESIA, Aresch.
(Possibly from µελιβοια [meliboia] or µηλοβοσις [melobosis], the daughter of Oceanus.)
Fronds calcareous, horizontally expanded, orbicular, becoming confluent and
indefinite in outline, conceptacles external or immersed; antherozoids spherical,
furnished with one or two short projections; tetraspores either two or four parted,
borne sometimes in conceptacles having a single orifice, at other times in
conceptacles having several orifices.
The limits of the three genera Melobesia, Lithophyllum, and Lithothamnion are not well defined. In M.
Thuretii, Bornet, the plant consists merely of a few short filaments, which are buried in the substance
of Corallina squamata and several species of Jania, upon whose surface the conceptacles of the
Melobesia are alone visible. From this species, in which the frond may be said to be rudimentary, we
pass through forms in which the frond is in the form of calcareous crusts or plates till we meet heavy,
irregularly branching forms, which resemble corals much more than plants. In the present paper,
Melobesia, including Lithophyllum of Rosanoff, comprehends all the smaller and thinner forms in
which the frond does not rise in the form of irregular tubercles or branches, while in Lithothamnion are
placed the branching and heavier species, referred by the older writers, as Linnæus, Ellis and Solander,
Lamarck, and others, to Millepora or Nullipora, and by Kützing to Spongites. Our common species, L.
polymorphum, which does not often branch, shows the insufficient basis on which the genera of this
group rest. Although there is considerable diversity in the structure of the fronds, the organs of
fructification, with some slight modifications of the antherozoids and tetraspores, are the same as in
Corallina and Jania. The most detailed account of the