CYSTOSEIRA. 1 7 



3. C. barbata, Turn. ; frond cylindrical, stem furnished 

 with elliptical knobs, each producing a branch many times 

 dichotomo-pinnate and filiform ; air-vessels lanceolate, chain- 

 like ; receptacles ovate-elliptical, mucronate. Grew. Alg. 

 Brit. p. 6 ; Hook. Br. Fl. ii. p. 265 j E. Bot. t. 2170. 



A native of the Mediterranean, said to have been gathered on the De- 

 vonshire coast by Hudson. Distinguished from the last species by the 

 receptacles being tipped with a spine-like point. 



4. C.fccniculacea, L. ; stem compressed, branches long, 

 slender, rough with hard points, repeatedly dichotomo-pin- 

 nate ; air-vessels small, solitary or two together, elliptic ob- 

 long, near the apices of the branches ; receptacles minute, 

 linear-lanceolate. Grev. Alg. Brit. p. 7 ; Hook. Br. Fl. ii. 

 p. 265 ; Turn. Hist. t. 252 ; E. Bot. t. 2130 and t. 2131 ; 



Wyatt, Alg. Danm. No. 51 ; Harv. Phyc. Brit. t. cxxii. 



On rocks in tide-pools: coasts of the South and S. West of England. 

 Jersey. Perennial. Summer. Frond \ 2 feet long ; stem destitute of 

 knobs, nearly cylindrical, 4 6 inches high, and bearing numerous, long, 

 sub-simple, slender branches, which are generally naked toward the base, 

 but in the upper part closely set with distichous, alternately pinnate or 

 sub-dichotomous, secondary branches. In the young stale, and especially 

 when growing in deep water, this plant is furnished with long, flat, pinna- 

 tifid leaves, 1 2 lines broad, midribbed, dotted, and irregularly serrated 

 at the margins, and then constitutes the Cys. discors of Agardh (Fucus dis- 

 cors, L. ; E. Bot. t. 2131); but these leaves, as was long since shown by 

 Mrs. Griffiths, and as has been confirmed by Turner, Greville, and subse- 

 quent observers, finally elongate and become branches, and the plant as- 

 sumes the appearance as above described. 



5. C.Jibrosa, Huds. ; stem woody, compressed, bushy, 

 very much branched; branches slender, alternately branched, 

 the upper ones repeatedly divided, and furnished with li- 

 neari-setaceous, flattish ramuli ; air-vessels elliptical, mostly 

 solitary, immersed in the branches remote from the apices ; 

 receptacles filiform, much elongated. Grev. Alg. Brit. p. 8 ; 

 Hook. Br. FL ii. p. 266; E. Bot. t. 1969; Wyatt, Alg. 

 Danm. No. 52. Harv. Phyc. Brit. t. cxxxiii. 



On rocks near low-water mark and in tide-pools : also in 4 15 fathom 

 water. Perennial. Summer. Frequent on the shores of England and 

 Ireland. Not found in Scotland. Root, a hard, spreading disk. Frond 

 three feet long or more; stem mostly undivided, gradually diminishing 

 upwards, and thickly set with distichous, alternate branches, slightly swol- 

 len at base, and furnished with one or two series of smaller ramuli, the ter- 

 minal ones being long and setaceous. Air-vessels larger than in any other 

 British species, and generally occurring near the base of the branches, so- 

 litary or two or three together. Colour olive-green. 



C 



