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and occupied by a lax network of fine filaments, articulated at remote
intervals. It is in this part that the globules of seeds are situated, and,
in some species at least, destitute of any orifice by which they might
escape. In tbe species figured by M. Bory in the botanical part of
Duperrey’s Voyage, an orifice appears to be present ; but, in this instance,
as well as in others, formerly mentioned, his analyses are so indefinite,
that little information can be gathered from them. In Fucus
bracteatus of Gmelin, I apprehend there is none. The globule of seeds
being enveloped in a tenacious gelatinous kind of limbus, favours tbe
idea, as it must escape entire if it escape at all, before the decomposition
of the part. The Fiicus palmatus of authors, I conceive neither
to be an Iridoea. according to Bory, nor an Halymenia, according to
Agardh, but rather a Rhodomenia ; the structure is diiferent, and tbe
fructification, as far as we know, is, as we have already seen, composed
of semi-imbedded ternate granules, exactly similar to those of the
genera Delesseria and Rhodomenia.
The generic name is expressive of the prismatic or iridescent tints
which most of the species reflect from their surface, while in a growing
state.
1. lllIDiEA EDULIS. Tab. XVII.
Frond between flesliy and coriaceous obovate rounded at the summit
(often cleft by the waves) attenuated below into a short stem.
Iridoea edulis, B o ry in D i e t . C la s s . d ’H i s t . N a t . v . i). p . 15.
Halymenia edulis, Ag. S p . A lg . v . 1. p . 202. S y s t. A lg . p .2 4 2 . S p r e n g . S p . P I . v . 4. p . 333.
Delesseria edulis, L am o u r . E s s a i, p . 38.
Viva edulis, D e c a n d . G re v . F I . E d in . p . 298.
Fucus edulis, S ta c k h . N e r . B r i t . p . 57. t . 12. T u m . S y n . F u c . p . 180. H i s t . F u c . t . 114.
S m . E n g . B o t. t . 1307. H o o k , in F I. L o n d . N ew S e r ie s , w i th a f ig u r e , ( th e a n a ly s is
in c o r r e c t.)
H ab . On rocks in the sea, generally near low water-mark. Biennial.
October. Menabilly, Fowey, Acton Castle. Penzance, &c.,
Stackhouse. Portluney, Carhayes, and on the coast of Hampshire,
Mr E. Foster junior. Torquay, Sidmouth, and many other places in
Devonshire. Coast of Anglesea, Rev- H. Davies. Near Abergele,
Mr Griffith. Rocks near the Caves at Dover, plentiful, Dillwyn.
Shore at Yarmouth, Mr Wigg. At Seaford and Brighton, rare, Mr
Borrer. Coast of Northumberland and Durham, Winch. Near Belfast,
Dr Drummond. Orkney Islands, Rev. C. Clouston. Shore at
Leith, Sir J. E. Smith. Frequent at low tides to the east of Prestonpans,
Dr Hasell. Many places on the western coast of Scotland.
Root an expanded tied disk. Plants tufted, numerous, rising for a
few lines with a cylindrical stem as thick as a crow-quill, then immediately
beginning to expand into a flat, obovate, or oblong wedge-shaped
frond, six to eighteen inches in length, and two to eight or ten inches
in width, smooth and glossy, much rounded at the summit, generally
split hy the action of the waves into two or several segments, sometimes
down to the base, the margin always flat and entire. Fructification
situate towards the extremity, in wide patches, sometimes occupying
the whole of the end for several inches, composed of spherical,
unequal clusters or globules of minute ovate seeds, immersed throughout
the central substance of the frond. Substance, thick and fleshy,
or somewhat coriaceous. Colour, a fine deep blood-red, paler in
young plants, changing in decay to green and dirty white. It adheres
to paper in drying, and generally becomes almost black, except when
held between the eye and the light, when it exhibits a fine purplish
red. Some specimens, however, scarcely change colour at all.
It is remarkable that this plant should have been long confounded
with Fucus palmatus of authors, an alga that I have found necessary
to remove even to another genus. This is the more difiicult to account
for, as both species are highly characteristic, especially that
under consideration, of which Mr Dawson Turner remarks, that he
knows of no one liable to fewer variations of shape.
It seldom happens that a specimen of Iridoea edulis of any considerable
size, can be procured entire. Though of a thick substance, it
is succulent and easily injured, and even when not split by the violence
of the waves, is generally perforated and mutilated by crabs and
other marine animals, to whom it is a grateful food. Much of its reputation
as a vegetable for the table, has arisen in consequencè of its
having been so long confounded with Rhodomenia palmata. It goes
by the name of Dulse in the south-west of England, according to
Stackhouse, and is eaten by the fishermen, either in a raw state, or
after having been pinched between hot irons, when it is said to taste
like roasted oysters. It is comparatively rarely eaten in Scotland, but
Mr Neill informs us, is sometimes preferred for roasting in the frying-
pan.
Mr Dawson Turner has justly remarked, that if it be moistened
after having been once dried, it becomes so tender, and imbibes so
much water, that it speedily decays, and can seldom support its own
weight, when held up by the root. Mr Stackhouse observed the frond
to give out a fine purple colour to the water in which it was macerat