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short intervals, with vesicles. Vesicles linear-lanceolate, about an inch
long, and one to two lines broad, compressed, supported on little
stalks about two lines in length, and terminated by a flat linear beak,
generally a few lines, but often as long as themselves. On the external
surface of the vesicles it is easy to perceive transverse furrows,
about a line asunder, indicating a similar number of dissepiments, by
which the interior is divided into many distinct cavities. Receptacles
situated at the summit of the branches, distichous like the vesicles, and
nearly of the same form, scarcely an inch long, linear-lanceolate, compressed,
pedunculate, the surface dotted with pores, communicating
with the immersed collections of seeds.
Substance coriaceous. Colour pale olive opake green.
In the young state, the plant is furnished with fiat linear leaves,
ahout a line broad and two inches long, traversed by an obscure midrib,
and entire at the margin: they soon pass into branches.
Tlie variety minor is commonly six to twelve inches in height, with
every part much smaller and narrower. Mr Turner also records
another variety which he names Demidata, having “ a very narrow
compressed stem, and long, thin, flat leaves, without any appearance
of their any where swelling into vesicles or pods: the width of the
plant is scarcely half a line, and nearly the same in all its parts.” I
fear that this variety, gathered at Weymouth by Mr Bryer, must be
denominated rather an extraordinary state of the plant, developed under
peculiar circumstances ; a point of view in which Mr Turner himself
regards it in the Synopsis Fucorum.
The larger states of this Alga are produced in deep water. Specimens
intermediate between variety minor and the common appearance,
I have gathered in a growing state in deep pools in the Isle of
Bute, two feet in length. At Sidmouth, in the winter 1827-8, I obtained
others from the sca-beach with the whole frond singularly broad:
the vesicles are oblong and one-third of an inch in breadth.
In some parts of Norway, this species, as well as Fucus nodosus, is
known by the name of Knoptang. It is not put to any use.
G e n u s IV. FUCUS. Linn. Ay. Tab. II.
G e n . C h a r . Frond plane, compressed or cylindrical, linear,
dichotomous, coriaceous. Air-vessels when present, innate
in the frond, simple, large. Receptacles terminal
(except in F. nodosus), turgid, containing tubercles imbedded
in mucus, and discharging their seeds by conspicuous
pores.
This genus, the name of which is derived from a Greek word, signifying
either a paint or dye, or a sea-weed, was applied by Linnæus
to almost every marine plant not comprehended in his genera Ulva
and Conferva, and remained entire for many years. At length (for it
is hardly worth while to describe the attempts of Donati, Adanson,
and Roussel) Decandolle broke in upon the old system, by transferring
from the genus Fucus to Ulva all those species which are destitute of
tubercular fructification. In 1813, M. Lamouroux divided the inarticulated
Algæ into two orders and seventeen genera, and laid the
groundwork of every succeeding arrangement ; but the plants he retained
under the original generic name of Fucus were obviously susceptible
of farther division ; and, accordingly, Agardh established some
new genera in his Synopsis Algarum Scandinavian, and Lyngbye
others in his Tentamen Hydrophytologioe Danicoe. Agardh, in his
two subsequent works, has made farther alterations ; and M. Gaillon,
in the Dictionaire des Sciences Naturelles, after adopting the
system of Lamouroux, suggests various changes, not perhaps in most
instances very judicious. The genus Fucus is, however, now pretty
well defined, and in Agardh’s Systema Algarum contains only fourteen
species, of which I have thought it right to exclude F. loreus and
F. rugosus,—the former will be found in this work under Himantha-
lia ; the latter I have made the type of a new genus, under the name
of Splachnidium. Fucus Banksii, Turn., which Agardh has referred
to Cystoseira, is also made the foundation of a distinct genus by M.
Bory de St Vincent.
The species are peculiarly coriaceous, and mostly of robust growth ;
the frond, when plane, is furnished with a midrib ; the vesicles are
large, hollow, with a single cavity ; the receptacles, when ripe, are
turgid with mucus, mostly of an elliptical form (in F. serratus, imbedded
in the flat extremities of the frond), and large size, the seeds and