- 
Ser. RHopOSPERME. Fam. Ceramiee. 
Puate XC. 
CERAMIUM NODOSUM, Grif. and Harv. 
Gun. Cuar. Frond filiform, one-tubed, articulated ; the dissepiments coated 
with a stratum of coloured cellules, which sometimes extend over the 
surface of the articulation. Lructification, of two kinds, on distinct 
individuals ; 1, ¢e¢raspores, either immersed in the ramuli, or more or 
less external; 2, sessile, roundish receptacles (favelle), having a pel- 
lucid limbus, containing minute, angular spores, and subtended by 
one or more short, imvolucral ramuli. Crramium (Roth),—from 
képapos, a pitcher, but the fruit is zo¢ pitcher-shaped. 
Ceramium nodosum; frond capillary, of equal diameter throughout, rigid, 
dichotomous, excessively divided, fastigiate; the axils very patent; 
articulations pellucid, those of the middle of the stem from four to six 
times as long as broad, the upper gradually shorter; dissepiments 
swollen ; tetraspores erumpent, two or three together on the outer edge 
of short, accessory ramuli; favellee at the apex of accessory ramul.. 
Hormoceras nodosum, Kitz. in Linnea, vol. xv (1841). p. 732. Kiitz. Phyc. 
Gen. p. 378. t. 45. f. 1-7 (showing the germination of a spore). 
CrRAMIUM diaphanum, rigid variety, Wyatt, Alg. Danm. no. 217. 
CERAMIUM rigidulum, Griff. and Harv. in Herb. 
CrRAMIUM, new species, Mc’ Calla, Alg. Hib. vol. i. no. 43. 
Has. On sandy shores, often at the roots of Zostera. Meadfoot, near Tor- 
quay, Mrs. Griffiths. Isle of Wight, Miss Kirkpatrick. Dublin Bay 
and Ireland’s Hye (1838), Miss Ball. Bangor (1835) and New- 
castle, Co. Down, Mr. W. Thompson. Howth, Miss Gower. Rath- 
mullar, Mrs. Ovens. Roundstone Bay, Mr. Me’ Calla. 
Geoer. Distr. Mediterranean Sea, Kiitzing. New York, Professor Bailey. 
| Tasmania, Ronald Gunn, Esq. 
Descr. Fronds springing many from the same base, and forming dense globular 
tufts, from three to six inches in diameter. Filaments very slender, finer 
than human hair, excessively branched from the base in a more or less 
regularly dichotomous manner, preserving an equal diameter throughout 
their length; more or less furnished in the upper part, especially in fertile 
specimens, with short ramuli. -Azz/s in all parts of the frond, very patent, 
sometimes divaricating. pices nooked inwards. Articulations colourless, 
five or six times as long as broad in the lower and middle branches, thrice as 
long as broad in the upper ; and gradually diminishing in length towards the 
apex. Dissepiments smooth (without prickles), globose, swollen, coated with 
a stratum of minute brownish-red cellules. Zetraspores formed in the disse- 
piments of short, lateral ramuli, roundish, with a wide border. Colour of 
the tufts, brownish-red. Substance rigid and harsh to the touch when 
recent ; soon becoming flaccid. It adheres, but not very strongly, to paper 
in drying. 
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