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P l a t e CXL.
CERAMIUM ACANTHONQTUM, Carm.
G en . C h .ie . Frond filiform, one-tubed, articulated ; the dissepiments coated
with a stratum of coloured cellules, which sometimes extend over the
surface of the articulation. Fructification of two kinds, on distinct individuals
; 1, tetraspores, either immersed in the ramuli, or more or
less external; 3, sessile, roundish receptacles { fa v e lla ) , having a pellucid
limbus, containing minute, angular spores, and subtended by one
or more short, involucral ramuli. Cekamium {Both),—from sepagos,
a pitcher, but the fruit is not pitcher-shaped.
Ce eam ium acanthonotmn-, frond slender, of nearly equal diameter throughout,
rigid, repeatedly dichotomous, fastigiate, the apices strongly
involute; articulations pellucid, those of the middle of the stem
several times longer than broad, the upper gradually shorter ; dissepiments
coloured, armed on the outer edge with a single robust, broadly
subulate, coloured, three-jointed prickle ; tetraspores erumpent, whorled
round the joint; favellæ roundish, subtended by a solitary, incurved
ramulus.
Ceeam ium acanthonotum, Cam. Alg. Appin. ined. cum ic. J. Ag. Advers.
p. 26.
Ceeam ium ciliatum, ^ . acanthonotum, Harv. in Hook. Br. M. vol. ii. p. 336.
Harv. Man. p. 100.
Acanthooeeas Shuttleworthianum, Kiitz. in Innn. t. 15. p. 739. Kiitz. Phyc.
Gen. p. 381. t. 46. f. 4.
H a b . On exposed rooks, near low-water mark, and on the smaller Algæ.
Annual. Summer and autumn. Not uncommon. Appin, Capt.
Carmichael. Aberdeen, B r . Bichie. Torbay, Mrs. Griffiths, Plymouth,
Messrs. Bore and Rohloff. Common in the west of Ireland, W .H .H .
Yonghal, Miss B a ll.
Geoge . Dis t e . The British Islands.
Desob. Fronds very densely tufted, when old forming intricate and often matted
hunches, from two to six inches in diameter, slender, ab o u t as thick as
human hair, of equal diameter throughout, excessively divided dichotomously
and more or less furnished with la te ra l dichotomous branchlets ; in old
specimens these la tte r become in th e ir tu rn repeatedly divided, and, issuing
along th e whole of th e lower p a rts of th e frond, serve to render the tu fts so
compact and closely matted, as they eventually become. Axils pa te n t in
all p a rts of th e f ro n d ; apices strongly roUed inwai’ds. Articulations
colourless, cylindrical, those of th e lower p a rts of th e stem several times
longer th a n broad ; the upper gradually shorter, and th e ultimate ones
extremely short, many times shorter th a n broad. Dissepiments coated with
a broad, deeply coloured, well-defined band of minute, angular cellules ;
each with a solitary, robust, coloured, three-jointed, broadly subulate, or
deltoid, very acute prickle on its outer margin. ^ Tetraspores veiy large,
with broad pellucid pericarps, erumpent from the joint, whorled. Favella
globose, lateral, subtended by a single, strongly incurved ramulus. Colour
of th e tufts dark purple. Substance rigid, imperfctly adhering to paper.
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