Ser. RHopOSPERME. Fam. Rhodomelea. 
Prate CCLXXXIV. 
POLYSIPHONIA BYSSOIDES, Grev. 
Gen. Cuar. Frond filamentous, partially or generally articulate ; joints 
longitudinally striate, composed of numerous radiating cells or tubes, 
disposed round a central cavity. . Fructification twofold, on different 
individuals ; 1, ovate capsules (ceramidia), furnished with a terminal 
pore and containing a tuft of pear-shaped spores; 2, ¢efraspores, im- 
bedded in swollen branchlets. Polysiphonia (Grev.),—from modus, 
many, and oper, a tube. 
PorystpHontia Jyssoides ; stems rigid, setaceous, cartilaginous, distichously 
branched, decomposito-pinnate ; branches patent, more or less densely 
clothed with short, slender, dichotomous, single-tubed, byssoid ra- 
melli ; articulations of the stem variable in ‘length, 3--4.striate. 
PotystPHONIA byssoides, Grev. Fl. Edin. p. 309. Harv. in Hook. Br. Fl. 
vol. ii. p. 334. Harv. Man. ed. 2. p. 92. Wyatt, Alg. Danm. No. 85. 
Harv. in Mack. Fl. Hib. part iii. p. 209. Endl. 3rd Suppl. p. 46. Kitz. 
Phyc. Gen. p. 430. 
Hurcurnsta byssoides, Ay. Sp. Alg. vol. ii. p. 99. 
ConFERvVA byssoides, Lng. Bot. t. 547. Diliw. Conf. t. 48. 
CeraMIuM molle, Roth. Cat. Bot. vol. iii. p. 138. 
Fucus byssoides, Good. § Woodw. Linn. Trans. vol. iii. p. 229. 
Has. On stones and shells, and various Alge ; near low-water mark and 
in 4—5-fathom water. Generally distributed on the English and Trish 
coasts ;—more rare in Scotland. Orkneys, Messrs. “Thomson and 
M‘Bain. Frith of Forth, Sir J. Richardson, &e. 
Geogr. Distr. Atlantic shores of Europe. Adriatic, C..4. Agardh. 
Descr. Root a small disc. Fronds from six to twelve inches long or more, as 
thick as hog’s bristle, with an undivided stem running through the whole 
plant, closely set throughout with distichous, alternate branches similar to 
the stem, and like it furnished with a second, and in large specimens a third 
series of lesser branches. The lower branches are longest, the rest gra- 
dually shorter upwards, so that the general outline of a “frond is broadly 
ovate, or pyramidal. All the branches and their divisions are clothed with 
short, byssoid, single-tubed, dichotomous ramelli (/eaves), which appear to 
be of the same nature as the fibres in which the young branches of all Poly- 
siphonie terminate. Every portion of the stem and branches is pellucidly 
articulate, the articulations 3-4-tubed, the transverse section exhibiting 
seven siphons; these articulations vary much in length in some specimens, 
being 4—6 times longer than broad, in others but twice or thrice exceeding 
their diameter: those of the smaller branches are usually short. Capsules 
ovate, sessile, scattered on the smaller branches. Tetvaspores immersed in 
the branchlets, each formed from an articulation. Colour a clear and beau- 
tiful crimson lake, becoming brownish on exposure, and commonly a dark 
