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106 THE MARINE ALGÆ OF NEW ENGLAND. and at the time, as there were no antheridia, we hastily inferred that the spores were non-sexual. It now seems probable that the plant is the V. litorea of Nordstedt, l. c., a diœcious species. The species was common at Wood’s Holl in August, 1879, but constantly sterile. The antheridia of V. litorea, Nordstedt, are long and cylindrical and borne on a short sterile cell at the tips of the branches. The antherozoids are discharged by openings at the apex and sides of the antheridium. Our plant will be easily recognized by its habit and the recurved branches bearing the oogonia. ORDER IV. FLORIDEÆ. Algæ of a red or purple color; antheridia containing spherical, hyaline antherozoids, which are without cilia; sexual fruit or cystocarps developed from a procarp, which consists of a trichogyne, at whose base is a trichophore, the spores formed either from the trichophore or the adjacent cells which compose the carpogenic system; spores at maturity either naked or inclosed in a pericarp; non-sexual reproduction by tetraspores, bispores, and seirospores; fronds filamentous, crustaceous, membranaceous, or irregularly expanded, varying from gelatinous to cartilaginous in substance, occasionally calcareous. Principally marine. The Florideæ, which are the same as the Rhodospermeæ of Harvey, include a large number of species, all of which have some shade of red, although it may be nearly black on the one hand or approach shades of green on the other. In decay, however, the color becomes orange and finally green. It is not to be inferred, however, that all red algæ belong to the Florideæ . There are a few Cyanophyceæ in which the color is pink, but in these species the frond is merely an agglomeration of red cells, each of which is practically a distinct individual, whereas in the Florideæ the cells are organically united, and constitute a single plant. The structure of the frond in this order varies in the different genera, and we have forms which correspond closely to the fronds of the Phæosporeæ, as, for instance, in Nemalion we have a frond which, apart from its color, is undistinguishable from that of Mesogloia, and so on. The non-sexual reproduction is by tetraspores, cells which divide into four parts—rarely by bispores or two-parted cells—and seirospores, or chains of oblong cells formed directly from the branches. The sexual fruit, known as the cystocarp, is developed from a procarp, as has already been explained. The division into suborders is founded principally on the differences in the cystocarpic fruit, the full development of which is not known in many cases. Differences in the fronds and tetraspores serve to mark the genera. Agardh and Harvey divide the Florideæ into two series—the Desmiospermeæ, in which the spores are arranged in a definite series with regard to a placenta or common point of attachment, and Gongylospermeæ, where the spores are heaped together without order. A study of the development, however, shows that this distinction has not the value which it was formerly supposed to have, and certain suborders with differently arranged spores are by those who lay stress upon the development placed in proximity to others in which the spores are irregularly grouped. Although, owing to modern researches, we know much more about the real nature of the cystocarps than was known a few years ago, it must be admitted that the suborders of Florideæ are far from satisfactory. As a matter of fact, the order is a very natural one, and, as is the case with most natural orders, the species and genera pass so gradually into one another that sharply marked divisions are out of the question. At the base of the order is a small number of genera whose position is doubtful, owing to our lack of information about the fructification. Then come the Porphyreæ, in which we have fronds of a single layer of cells (Porphyra) and certain cells grow out so as to form a very short
REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 107 trichogyne. After fertilization, the contents of the cell at the base of the trichogyne divide, quadrant fashion, and we have a number of spores produced at once from the original cell. In Nemalion the trichophore, or swollen base of the trichogyne, divides, and the divisions grow out laterally and form short filaments, each cell of which becomes a spore, so that at maturity the cystocarpic fruit consists of a dense tuft of radiating, moniliform filaments. In the Ceramieæ we have favellæ, or cystocarps, in which the carpogenic cells bud out and produce several lobes, each of which divides into a number of very short filaments, which do not separate from one another, but remain adherent. The cells of the filaments are changed into spores, which form irregular groups, but are still held together by the mass of jelly which surrounds them. In the more highly developed suborders the spores either radiate in filaments from a sort of placenta which is produced from the carpogenic cells or else are terminal on short stalks. The pericarps are special sacks or conceptacles, inclosing the spores and developed from the cells below the procarp, or we may have the cystocarps borne in the interior of solid fronds, whose external portion may then be said to form a pericarp around them. It will be seen that the structure of the Florideæ is more complicated than that of the other orders of algæ, and the student cannot expect to obtain a clear idea of the different suborders without considerable study. The folio wing key will aid somewhat, and the reader should consult the plates appended to this paper: 1. Spores formed in the cells of the frond itself ............................... Porphyreæ. 2. Spores (cystocarps) not formed directly from the cells of the frond, but from a special procarp .................................................................................................................... 3 3. Spores without a special covering or pericarp .............................................. 4 Spores with a special covering....................................................................... 10 4. Spores naked ................................................................................................. 5 Spores immersed in the frond ........................................................................... 7 Spores immersed in external warts ................................................................... 6 5. Spores free on the surface of a lobulated mass .................. Spermothamnieæ. Spores irregularly grouped in masses which are surrounded by a gelatinous envelope............................................................................Ceramieæ. 6. Fronds erect, cylindrical........................................................ Spongiocarpeæ. Fronds horizontally expanded........................................................ Squamarieæ. 7. Spores arranged in dense tufts of radiating moniliform filaments . Nemalieæ. Spores on an axile placenta in swollen branches .................................Gelidieæ. Spores in numerous radiating tufts around a central placenta or carpogenic cellSolierieæ. Spores arranged without order .......................................................................... 8 8. Spores forming a single mass or nucleus and entirely buried in the frond.... 9 Spores in several masses, separated by the tissue of the internal part of the frond and rising in swellings above the surface.......................................................Gigartineæ. 9. Fronds hollow and tubular ...........................................................Dumontieæ. Fronds solid.................................................................................Cryptonemieæ. 10. Spores arranged without regular order...................................................... 11 Spores in small, scattered tufts, borne on branching filaments— Hypneæ. Spores in radiating moniliform filaments ........................................ 12
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