can be mistaken. In some situations it is very liable to lose the extremities
of the branches, which then become obtuse, somewhat thickened
and erose, frequently also of a greenish hue. It gives out a pink
dye very freely on immersion in fresh water, and is apt to stain the
paper, under pressure, the same colour.
G e n u s XLVI. CATENELLA, Grev. Tab. XVII.
G e n . C h a u . Fronds filiform somewhat compressed, creeping,
throwing up numerous branches, contracted as if
jointed in a moniliform manner, composed interiorly of
branched filaments radiating from the centre. Fructification
unknown.
Obs. The peculiarity ot the internal structure of this alga has induced
me to sepai'ate it from all others, even in the absence of fructification,
and, in conjunction with its habit, to place it among the Ga s -
TRoCARPEiE. It has ever been considered in the light of a doubtful
plant, and has succesively held the title of Ulva, Fucus, Rivularia,
Gigartina, Chondria, Halymenia, Lomentaria, and, lastly, mirahile
dictu, of Chordaria in Sprengel’s ‘ Systema Vegetabilium !’ I have endeavoured—
not I think without sufficient cause - to afford this almost
universal trespasser, something more like a “ local habitation and a
name.”
The generic name signifies a little chain, in allusion to the chain or
necklace-like form of the frond.
1. Ca t e n e l l a O p u n t ia . Tab. XVII.
Chordaria Opuntia, S p r e n g . S p . P I. v . 4. p . 330.
Lomentaria Opuntia, G a ill. D i e t . d ’H i s t . N a t . v . 53. p . 36?.
Halymcniaf Opuntia, Ag. S p . A lg . v . I . p . 21? . S y s t. A lg . p . 245.
Chondria Opuntia, H o o k . F I . S c o t. P t . 2. p . 106. G r e v . F I. E d in . p . 292.
Gigartina Opuntia, L am o u r . E s s a i, p . 49.
Gigartina pilosa, L a in o u r . E s s a i, p . 49, a c c o rd in g to sp e c im e n s s e n t to A g a rd h .
Rivularia Opuntia, Sm . E n g . B o t. t. 1868.
Fucus Opuntia, G o o d e n , a n d W o o dw . in L in n . T r a n s v . 3. p . 209. T u r n . S y n . F u c . n . ,107.
H i s t . F u c . t . 107.
Fucus coespitosus, S t a c k h . N e r . B r i t . p . 59. t. 12.
Fueus repens, L ig h t f . F I . S c o t. p . 961.
Viva articulata, v a r . g- H u d s . F I. A n g . p . 569.
H a b . On sea side rocks within high water-mark. Perennial. Coasts
of Devonshire and Cornwall, Mrs Griffiths. On the naked rocks at
St Michaefs Mount Pier, and at Tenby, in South Wales, Stackhouse.
In the Blackwater at Maldon, Essex, Mr E. Forster junior. Rocks
opposite Priestholm Island, Anglesea, Dillenius. Shores of the Isle
of Wight, Mr Maimburg. Hastings, Turner. On the rocks about
Dover, Billwyn. Coasts of Durham and Northumberland, Winch.
Bay of Dublin, Dr Scott. Bantry Bay, Miss Hutchins. Near
Musselburgh, in Scotland, Lightfoot. Many other places on the shores
of the Frith of Forth, and common on the western coast of Scotland.
Orkney Islands, Rev. C. Clouston.
Root creeping, passing insensibly into the fronds, which are densely
matted and entangled, half an inch to one inch in height, scarcely half
a line in thickness, between cylindrical and compressed, more or less
contracted at intervals, so as to resemble a chain or necklace, the joints,
if so they may be termed, generally becoming larger towards the apex of
the branches: branches suberect, arising from the creeping stem without
order, simple or divided, the summits obtuse, or sometimes terminating
in a slender somewhat tendril-like prolongation. Within, the frond
is composed of a lax tissue of dicbotomously branched jointed filaments,
the branches divaricated and numerous, radiating, as it were from the
centre to the circumference of the frond; for they are horizontally disposed,
and the joints become smaller and smaller, till their extremities
terminate in the substance of the external coat of the frond. Fructification,
unknown. Substance membranaceous or slightly cartilaginous,
soft, tender, and full of moisture. Colour, a dark, livid, somewhat
transparent purple, the creeping portion much paler. In drying, it
becomes darker, and adheres imperfectly to paper.
The fructification of this small species is involved in the greatest
obscurity. Lightfoot and others, imagined that the joints, formed by
the contractions of the frond, were full of minute seeds, and performed
the office of capsules. Sir James Edward Smith believed the smaller
joints of the internal filaments to contain the seeds. Mr Dawson
Turner describes certain minute black bodies, which are not unfre-
quent on the frond, as doubtful fructification. None of these, however,
appear to me to be true fructification.
In regard to the habit of growth, it is ordinarily found on the perpendicular
sides of rocks and blocks of stone, especially in crevices
and spots least exposed to the sun. In such situations, it covers large
spaces, extending itself like a mat. The species that comes nearest to
it in this respect, is variety clavatum of Gelidium corneum, which is
often found iu its neighbourhood, as well as Ceramium Rothii, Calo-
thrix scopidorum, and both species of Lichina.
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