Ser. RHODOSPERMEZ. Fam. Ceramiee. 
Puate CXCIII. 
CERAMIUM DIAPHANUM, Rozz. 
Gen. Cuar. 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, ¢etraspores either immersed in the ramuli or more or 
less external; 2, sessile, roundish receptacles (favelle), having a 
pellucid limbus, contaming minute, angular spores, and subtended 
by one or more, short, involucral ramuli. Crramium (foth.),— 
from xepapos, a pitcher; but the fruit is not pitcher-shaped. 
Crramium diaphanum; filaments setaceous, attenuated upwards, rather 
flaccid, irregularly dichotomous, the lower forkings distant, the upper 
close together ; branches set with short, lateral, dichotomous ramuli ; 
articulations colourless, those of the main stems three or four times 
as long as broad, of the ramuli short; dissepiments swollen, opake ; 
apices hooked inwards ; tetraspores whorled in the joints, depressed ; 
favellze in the ultimate forkings of the branches, or on lateral ramuli, 
mvolucrate. 
Ceramium diaphanum, Roth, Cat. Bot. vol. iii. p. 154. 4g. Syn. p. 61. 
Hook. Fl. Scot. part 2. p. 85. 4g. Syst. p. 133. Ag. Sp. Alg. vol. ti. p. 150. 
Grev. Fl. Edin. p.310. Harv. in Hook. Br. Fl. vol. ii. p. 336. Wyatt, 
Alg. Danm. no. 87. Harv. im Mack. Fl. Hib. part 3. p.210. Harv. Man. 
p- 99. J. dg. Alg. Medit. p.81. Endl. 3rd Suppl. p. 27. 
Hormoceras diaphanum. Ky. Phyc. Gen. p.378. Kg. Linn. xv. p. 733. 
Conrerva diaphana, Lightf. Fl. Scot. p.996. Fl. Dan. t.951. Roth. Fi. 
Germ. p. 525, and Cat. vol. i. p. 226. Dillw. Conf. t. 38. E. Bot. t. 1742. 
With. vol. iv. p. 139. 
Conrerva nodulosa, Huds. Fl. Ang. p. 600. 
Boryna diaphana, Grat. Dict. Class.t.11. Bory, Morée. p. 77. no. 1797. 
Has. Parasitical on several of the smaller Alge in rock-basins, between 
tide marks; sometimes growing on rocks. Annual. Summer. Not 
uncommon on the British coasts from Orkney to Cornwall. 
GsoeR. Distr. Dispersed throughout the temperate parts of the Atlantic and 
Pacific Oceans. (The various localities given require re-examination, as several 
species are commonly confounded by authors under the name diaphanum.) 
Mediterranean and Black Seas, 4g. 
Descr. Root minute, discoid. Fronds, three to six or eight inches long, not very 
densely tufted, setaceous at base, gradually attenuated upwards to a capil- 
lary fineness, more or less regularly dichotomous, or flabellately branched, 
sometimes alternately divided with an evident main-stem; the branches 
naked, or set with slender, forked, or several times dichotomous, short 
ramuli, one to three lines in length. Apices hooked in. Lower axils dis- 
tant, spreading; upper gradually closer and more erect. Articulations 
