Ser. RHoDOSPERME. Fam. Gasterocarpee. 
Puate LIX. 
| DUMONTIA FILIFORMINS, Grev. 
Gen. Cuar. Frond cylindrical, membranaceous, filled with watery gelatine, 
tubular ; its walls composed externally of minute roundish cells, inter- 
nally of elongated cellules, disposed in filaments. ructification of 
two kinds, on distinct individuals; 1, roundish ¢e¢raspores immersed 
in the surface cellules; 2, clusters of obovate spores attached to the 
inner surface of the membrane of the frond. Dumont1a (Lamour.)— 
in honour of M.Dumont, a French naturalist. 
Dumontra jfiliformis; frond undivided, attenuated to each extremity, 
pinnated with long, simple, tapering branches. 
Dumont1A filiformis, Grev. Alg. Brit. p. 165. +t. xvii. Hook. Br. Fl. vol. ii. 
p- 308. Wyatt, Alg. Danm. no. 31. Harv. in Mack. Fl. Hib. part 3. p. 188. 
Harv. Man. p.51. Hook. fil. Fl. Ant. parti. p.189. Kiitz. Phyc. Gen. 
p. 394. t. 74. f. 2. Endl. 3rd Suppl. p. 39. 
DumonmT1a incrassata, Lam. Ess. p. 45. 
HatyMeEnta filiformis, 4g. Sp. Alg. vol.i. p. 214. Syst. p. 245. 
CHoNDRIA purpurascens, Grev. Fl. Edin. p. 290. 
Gastripivum filiforme, Lyngb. Hyd. Dan. p. 68. t. 17. 
ConFerva filiformis, FZ. Dan. t. 1480. f. 2. 
Unya filiformis, Wahl. Fl. Lapp. p. 508. 
Var. 8. crispata; frond broad, compressed, waved, curled and twisted. 
Dumont14 filiformis 8. crispata, Grev. Alg. Brit. p. 165. Harv. l.c. 
HALYMENIA purpurascens £. crispata, Grev. Crypt. t. 240. 
Has. On rocks and stones in the sea, at half-tide level. Annual. Summer. 
8. in places exposed to tidal currents. Common. 
Geogr. Distr. Shores of Europe. Southern Ocean. 
Descr. Root, a small dise. Fronds solitary or tufted, from one to twenty inches 
in length, and from a tenth of an inch to half an inch in width, cylindrical 
or compressed, tubular, with an undivided stem furnished with alternate or 
irregularly disposed, lateral, simple branches; both stem and branches 
tapering at the base, and much attenuated towards the extremities, more or 
less waved, and flexuous. Sometimes the main stem is short, and compa- 
ratively slender; the branches being much longer, and of greater diameter : 
sometimes the branches are short, and the stem long. In almost all cases 
the tube is unequally distended or wavy, a peculiarity which in var. £. is 
very much exaggerated. In this the frond is much twisted, often in a strong 
spiral, and the membrane excessively curled and puckered. ructification ; 
1, tetraspores (which I have not seen); and clusters of obovate spores 
attached to the inner surface of the tube, abundantly produced in summer. 
Substance membranaceous, gelatinous within, adhering to paper in drying. 
Q 
