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144
THE MARINE ALGÆ OF NEW ENGLAND.
cruciate or zonate, usually collected in nemathecia or in superficial spots (sori),
sometimes scattered; cystocarps composed of numerous masses of irregularly placed
spores, between which are found portions of the tissue of the interior of the frond,
the whole sporiferous mass being covered by the swollen surfaces of the frond, which
are sometimes raised in subspherical conceptacles; spores discharged through
special carpostomes.
A large suborder, comprising species which are sometimes more or less cylindrical in shape, but which
are more frequently expanded and of a coarse, subcartilaginous consistency. Some of the largest
Florideæ are found among the Gigartineæ, and perhaps no other suborder contains so many ill-defined
species as the present. Owing to the thickness and opacity of the fronds, the study of the development
of the cystocarps is attended with very great difficulty, and as yet no fall account of the formation of the
fruit of any of the species has been published. In the Notes Algologiques, Bornet, however, gives a brief
account of the formation of the cystocarp in Gymnogongrus patens. In all the species the spores are
irregularly grouped in several distinct masses, which are imbedded in the tissue of the frond, the cells
of which undergo a change as the spores ripen, their walls becoming thick and lamellated, and
traversed by numerous small canals. In Callophyllis and some other genera the sporiferous mass and
the enveloping tissue of the frond form subglobose swellings external to the surface of the fronds, but in
other genera, as Gymnogongrus, the sporiferous mass occupies the central part of the frond, which
swells on all sides. The cystocarps discharge their spores through carpostomes or narrow canals formed
in the cortex of the fronds. Sometimes there is a single carpostome, but in some genera, as
Gymnogongrus and Ahnfeldtia, there are several.
1. Fronds terete.................................................................................................. 3
2. Fronds compressed........................................................................................ 4
3. Substance rigid, horny................................................................... Ahnfeldtia.
Substance soft, succulent ............................................................. Cystoclonium.
4. Fronds thin, leaf-like.................................................................. Phyllophora.
Fronds cartilaginous or subcartilaginous .......................................................... 5
5. Cystocarps external in special leaflets ........................................... Gigartina.
Cystocarps immersed ........................................................................................ 6
6. Central part of frond composed of roundish polygonal cells.
Gymnogongrus.
7. Central part of frond formed of slender anastomosing filaments.
Chondrus.
PHYLLOPHORA, Grev.
(From φυλλον [phyllon], a leaf, and φερω [phero], to bear.)
Fronds stipitate, stipes expanding into a rigid-membranaceous, flat, simple or cleft
lamina, proliferous from the disk or margin, composed internally of oblong polygonal
cells, with a cortical layer of minute, colored, vertically seriated cells; antheridia
contained in small cavities; tetraspores cruciate, arranged in moniliform filaments,
which are packed together in external excrescences (nemathecia); cystocarps