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As only a single and imperfect specimen of this species has come
under my observation, any account of it must be indulgently received.
Though we are acquainted only with the capsular mode of fructification,
yet I do not see how it can be referred with propriety to any other genus.
Its structure is dense, and very similar, under the microscope, to that of
Rhodomenia palmata,—but the different colour, and the fructification,
besides its greater thickness, at once remove it from that plant.
Under a high magnifying power the surface seems to be pitted (an
appearance too strongly represented by the engraver in the Cryptogamic
Flora), but it is impossible to say whether the same character
exists in the fresh state.
Is it possible that this plant can have any relation with the Fucus
Sarniensis of Professor Mertens ?
Since the description of this plant was prepared for the press,
Mr Walker Arnott has informed me that he found lately a specimen
in Whitsand Bay, Devonshire. He thinks it is really the Fucus
Sarniensis of Mertens and Roth. Having no access to the Catalecta
Botanica, in which that species was published, I regret that I camiot
determine the question. It is certainly possible that the Fucus Sarniensis
of Turner, which is a variety of R. palmata, may not be the
true plant of Professor Mertens.
4. R h o d o .m e n ia P a l m e t t a . Tab, X II,
Stem cylindrical filiform subsimple expanding into a fan-shaped
semicircular frond divided throughout in a dichotomous or palmate
maimer the segments linear with entire margins the axils rounded,
capsules imbedded in the disk and margin.
Sphanococcus Palmetta, Ag. S p . A lg . v. 1. p . 245. S y s t. A lg . p . 215. S p r e n g . S p . |*I.
V. i. p . 335.
Delesseria Falmetta, L am o u r . E s s a i, p . 37-
Halymenia Palmetta, G a ill. D ie t. S c . N a t . v . 53. p . 361.
F u c u s P a lm e t ta , p s p . Ic . F p c . p . 84. t. 40. e x c lu d in g a ll th e s y n o n ym s . S t a c k h . N e r .
B r it. p . 102. t. 16. Sm . E n g . B o t. t. 1120. T u m . S y n . F u c . p . 21. H is t. F u c . t . 73.
F u c u s bifidus, H u d s . F I. A n g . p . 58L
H a b . In the sea, growing upon rocks and the large stems of Laminaria
digitata. Annual. Sum.mer and autumn.
Root a red cartilaginous disk, often accompanied by a few creeping
fibres, and producing numerous stems. Stem from one or two lines to
an inch in length, simple or giving off a few branches, expanding more
or less gradually into a frond one to three inches long, which is generally
wedge-shaped or semicircular, and often so much dilated in its
outline as to exceed its length in its width. The segments into which
the frond is divided, are from one to tliree lines in breadth, and mostly
linear, but sometimes several divisions are compressed into so small a
space that the linear character is lost ; the margin is always entire,
and the apices are generally obtuse, or even rounded, rarely somewhat
elongated and rather acute, still more rarely somewhat laciniate.
Fructification ; 1. hemispherical red capsules, nearly as large as turnip-
seed, and sessile in the disk and margin of the frond : 2. ternate granules
minute, on distinct individuals, forming a cloud-like transverse
spot at the very extremity of the ultimate segments.
Substance cartilaginous in the stem, thin, semitransparent and membranaceous
in the frond, becoming darker and adhering imperfectly to
paper in drying. Colour varying from fine rose pink to nearly a crimson
red.
The ternate granules were discovered in this species by my friend
Mrs Griffiths, and are sufficiently obvious to be detected by the naked
eye. They seem to occur far more frequently than the capsules, and
are often situate in what appears to be a proliferous extension of the
apex of the frond, of an obcuneiform or obovate figure, and from two
to three lines in length.
R. Palmetta is placed by Agardh in that group of the genus
Sphoerococcus of which his S. crispus is the type ; but it must be confessed
it associates with its neighbours neither in substance, colour,
nor fructification. With S. membranifolius it might sometimes be
possible to confound it, were the mere outline alone to be regarded ;
but that species has always a livid purplish hue, never present m any
of the species of Delesseria, Nitophyllum, and Rhodomenia, not to
mention the totally distinct fructification.
5. R h o d o m e n ia c r is t a t a .
Frond semicircular membranaceous subdichotomous the segments
somewhat dilated upwards repeatedly subdivided the divisions alternate
decurrent laciniate at the ends, capsules spherical imbedded m
tlie margin of the frond.
Sphoerocoecus cnetatue, Ag . L y n g b . H y d r o p h . D a n , p . 13. t. 4. Ag. S p . A lg . v . 1. p . 3W.
S y s t. A lg . p . 231. G r e v . C r . F I. t . 86. F I . E d in . p . 296. S p r e n g . S p . P I . v . 4. p . 336.
Vueus crietatns, L in n . H e rb . T u r n . H is t. F u c . t . 23. e x c lu d in g v a r . y -
H ab. In the sea, upon the stems of Laminaria digitata.- Annual.
July. On the sea-shore at Wick, Caithness, Messrs Borrer and
Hooker. Frith of Forth.