Ser. RHoposPERME®. Fam. Rhodomelea. 
Prats CCLXXVII. 
POLYSIPHONIA NIGRESCENS, Grev. 
Gen. Cuar. Frond filamentous, partially or generally articulate; joints 
longitudinally striate, composed of numerous radiating cells or tubes, 
disposed round a central cavity.  Fruetification twofold, on different 
individuals: 1, ovate capsules (ceramidia) furnished with a terminal 
pore, and containing a tuft of pear-shaped spores; 2, ¢etraspores 
imbedded in swollen branches. PotystpHonta (Grev.), — from 
Todvs, many, and oper, a tube. 
PotystPHoNtA nigrescens; fronds robust, rigid, and generally rough with 
broken branches below, much branched and bushy above; the 
branches alternate, repeatedly divided in a pinnate manner; ramuli 
distant, elongated, awl-shaped, alternate, the upper ones sometimes 
having a few processes near the tips; lower articulations short, upper 
rather longer than broad; siphons about twenty, surrounding a large 
tube ; ceramidia broadly ovate, sessile or nearly so. 
PoLysIPHONIA nigrescens, Harv. in Hook, Br. Fl. vol. ii. p. 332. Wyatt, 
Alg. Danm.no.135. Harv. in Mack. Fl. Hib. part 3. p. 208. Harv. Man. 
ed. 1. p. 88. ed. 2. p. 89. Endl. 3rd Suppl. p. 45. Kiitz. Phyc. Un. p. 421. 
t. 50. iv." Sp. Alg. p. 813. 
PoLysIPHONIA fucoides, Grev. Fl. Edin. p. 308. 
Hureninsia nigrescens, Lyng. Hyd. Dan. p.109. 1.33. Ag. Syst. p. 151. 
4g. Sp. Aig. vol. ii. p. 69. 
Hourcurnsta fucoides, Hook. Fl. Scot. part 2. p. 87. 
ConFrerva nigrescens, Huds. Fl. Ang. p. 602. (??) Dillw. Conf. no. 155. Eng. 
Bot. t. 1717. 
' Conrerva fucoides, Huds. Fl. dng. p. 603. With. vol.iv. p. 141. Dillw. 
Conf. t. 715. Eng. Bot. t. 1743. . 
Has. On rocks, and stones, and attached to Alge, &c., between tide- 
marks. Perennial? Summer. Abundant on the British shores. 
Grocer. Distr. Atlantic shores of Europe and America. New Zealand. 
Descr. Root a small, discoid expansion. Fronds many from the same base, 
from three to twelve inches long or more, sometimes very slender and almost 
capillary, sometimes robust, twice as thick as hog’s bristle, simple below, 
very much branched and bushy above. The ramification, like almost every 
other character of this variable plant, is subject to many anomalies. In 
what may be considered the typical form, the stem divides into several 
principal branches, and the frond when displayed is broadly flabelliform in 
outline. Each main branch is obovate, and closely pinnated with alternate, 
erecto-patent secondary branches of similar outline; and these latter are 
doubly pinnate. The ultimate pinnules are subulate, distantly placed, 
regularly alternate, rather erect, and either quite simple or having one or 
