THE GENUS POLYSIPHONIA. 297 
II. CORTICATE SPECIES. 
A. Four primary pericentral siphons. 
1. P. enoncara (Huds.) Harv. in Smith's Engl. Flora, v. 1833, p. 333. 
P. Ruchingeri Kütz. Tab. Phye. xiv. 1864, p. 2, tab. 6 (a-d). 
Hutchinsia strictoides Lyngb. Tent. Hydrophyt. Danicæ, 1819, p. 114. 
P. trichodes Kütz. Tab. Phye. xiv. 1864, p. 4, tab. 10 (e-g). 
P. robusta Kütz. l.c. p. 4, tab. 11 (a-e). 
P. stenocarpa Kütz. l. c. tab. 11 (d-f). 
P. arborescens Kütz. l. c. p. 4, tab. 12 (ac). 
P. chalarophlwa Kütz. l. c. p. 5, tab. 12 (d-f). 
P. macroclonia Kütz. l. e. p. 5, tab. 13 (d, e). 
P. rosea Grev. Fl. Edin. 1824, p. 310. 
P. clavigera Kütz. l e. p. 5, tab. 14 (a-d). 
Hutehinsia elongata C. A. Ag. Syn. Alg. Scandin. 1817, p. 54. 
Ceramium elongatum Grev. Fl. Edin. 1824, p. 310. 
Ceramium brachygonium Lyngb. Tent. Hydr. Dan. p. 118. 
Conjerra elongata Huds, Fl. Angl. ed. II. ii. 1778, p. 599. 
References. Agardh (2) ii. p. 1004; De Toni (22) iv. p. 903 ; Falken- 
berg (24) p. 126 et seg.; Hauck (31) p. 227 et seq. 
Icones, Harvey, Phye. Brit. pls. 292 & 293. syn. 114. Kützing, Tab. 
Phye. xiv. le.  Exsiccatw. Desmazicres, exs. no. 1210, 1842. Crouan, Alg. 
mar. Finist. no. 301, 1852. Lloyd, Alg. Ouest Fr. nos. 55 & 305, 1854. 
Wyatt, Alg. Damnon. no. 40. 
DaschiPTION.— Habit. Plants usually solitary, 15-30 cms. long. Branches 
naked during the winter, clothed in spring with dense mass of ramuli. 
Branehing alternate with sometimes a tendency to pseudo-dichotomy. 
Ramuli attenuate at base and apex. Main branches cartilaginous in texture, 
ramuli gelatinous. Siphons. 4 primary pericentral, alternating with which 
on the outside are 4 secondary. Surrounding these in the older parts 
eight tertiary siphons occur, bounded by a zone of corticating cells. 
Colour. Reddish-brown, very dark in the older parts; ramuli crimson. 
Anatomy. Articulations obscured in the older parts of the main axis by the 
dense band of peripheral corticating cells. In the smaller branches and 
ramuli articulations 14 to twice as long as broad. Protoplasmic continuity 
maintained throughout the thallus, fibrillæ passing through pits in the 
contiguous walls. Attachment organ. Base of main axis expanding into a 
dise formed by the activity of the siphons and corticating cells. Each of the 
cells and siphons at the base becomes elongated into a thick-walled rhizoid, 
the extreme base of which flattens out and attaches itself to the substratum. 
Reproductive organs. Tetraspores borne in lateral and terminal ramuli, which 
are swollen and distorted. Cystocarps borne on small branches, sessile or 
very slightly stalked, ovate in form but tending to be elongated. 
