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REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 165
borne in parallel rows. Such collections of tetraspores are called stichidia. The fronds in the present
suborder vary greatly. In the more beautiful genera of tropical regions they are in the form of
complicated net-works or in membranes in which the cells are arranged in regular order, but in the
majority of the genera the fronds are filiform and branching and generally beset, at least at some
seasons, with delicate hairs. In most of the genera represented on our coast the fronds have a
polysiphonous axis, that is, on cross-section there is seen to be a central cell surrounded by a circle of
large cells, and in longitudinal sections there is a central filament composed of large cells, and on each
side a lateral filament whose cells correspond in length to those of the central filament, the upper and
lower walls of the three cells forming two parallel lines.
Fronds flattened ................................................................Odonthalia.
Fronds filiform .....................................................................................1
1. Tetraspores borne in the smaller branches..................................2
Tetraspores borne in stichidia ......................................................4
2. Superficial cells small, irregularly placed ....................................3
Superficial cells, at least in the younger branches, in transverse bands Polysiphonia.
3. Branches filiform throughout ..................................... Rhodomela.
Ultimate branches club-shaped, much attenuated at base. Chondriopsis.
4.Fronds beset with monosiphonous branchlets .......................Dasya.
Fronds without monosiphonous branchlets, superficial cells quadrate Bostrychia.
CHONDRIOPSIS, J. Ag.
(From χονδρος [chondros], cartilage, and οψις [opsis], an appearance.)
Fronds brownish red, terete or subcompressed, pinnately decompound, branches
virgate, much constricted at the base, composed of a monosiphonous axis surrounded
by a few (4-6) siphons and surrounded by secondary siphons, cortex of small
polygonal cells; antheridia borne in short disk-like branchlets covering both surfaces
except at the margin; tetraspores tripartite, in club-shaped branchlets; cystocarps
sessile, ovate, with a distinct carpostome, spores pyriform, on short pedicels from a
basal placenta.
A genus of which about twenty species have been described, which inhabit principally the warmer parts
of the world, some being widely diffused. They are as a whole difficult to distinguish, the specific marks
being principally the ramification and shape of the branchlets, points in which the different species
vary very much. The antheridia are very peculiar. On the upper branches are borne flattened, more or
less incurved, disk-shaped branches, whose margin is wavy. The antheridia cover both sides of these
discoidal branches, except at the margin, which is composed of large hyaline cells. The fronds are
intermediate between those of Rhodomela and Laurencia, and the branchlets are always much
constricted at the base. Most of the species were formerly included by Lamouroux and others in the
genus Laurencia. By C. A. Agardh they were, in the Species Algarum, placed in Chondria, a genus
retained by Harvey in the Nereis. Since as originally defined the genus Chondria embraced algæ of
rather remote relationship to one another, J. G. Agardh, in the third volume of his Species Algarum,
separated the present group, under the name of Chondriopsis, the name Chondria being