THE GENUS POLYSIPHONIA. 299 
intercalary in development, borne in the tips of the branches and ramuli. 
Cystocarps large, stalked, ovate in form, with a tendency to elongate near the 
ostiole. 
P. elongella often resembles P. elongata, but may be distinguished by the 
visibility of the articulations in all parts of the plant except the extreme base, 
cortication being less well developed in the former species. Also, the ramuli 
of P. elongella are not attenuate at the base as in P’. elongata, According to 
Harvey (l. e. p. 113), Hauck (l.e. p. 228), and De Toni (l c. p. 910), there are 
4 pericentral siphons in each articulation, surrounded by a band of * cellules." - 
It is evident, however, that 4 secondary siphons alternate on the outside with 
the 4 primary ones, before the corticating cells begin, these siphons differing 
from the cells in the fact that they occupy the whole length of an articulation. 
Habitat. On rocks, stones, and smaller algæ near low-water mark and 
at greater depth. Rare, though widely distributed. 
British Records. Kirkwall Bay, Peterhead, Elie, Brighton, Bognor, Isle 
of Wight, Swanage, Weymouth, Sidmouth, Torbay, Plymouth, Torpoint, 
Talland Bay, Falmouth, Padstow, Anglesea, Isle of Man, Saltcoats, Seamill, 
Ardrossan, Arran, Cumbrae, Kirn, Larne, Belfast Lough, Malahide, Howth, 
Killiney, Bantry, and Jersey. 
Distribution in Europe. Coast of France and Adriatic Sea. 
3. P. FIBRATA Harv. in Smith's Engl. Flora, v. 1833, p. 329. 
Hutchinsia allochroa B. fibrata C. A. Ag. Syst. Alg. 1824, p. 154. 
Grammita decipiens Bonnem. Hydroph. loc. 1822, p. 37. 
References. Agardh (2) ii. p. 965 ; De Toni (22) iv. p. 893. 
Icones, Harvey, Phye. Brit. 1846-51, pl. 208. syn. 109. ÆExsiccatæ. 
Cróuan, Alg. mar. Finist. no. 294, 1852. Lloyd, Alg. Ouest Fr. no. 193, 
1854. Wyatt, Alg. Damnon. no. 39. 
Description.—Habit. Oceurring in tufts 20-23 ems. in length. Branching 
either alternate or pseudo-dichotomous, main branches being clothed with 
numerous ramuli, frequently bearing delicate fibrillæ at their tips.  Siphons. 
4 pericentral round a minute central one, a row of corticating cells 
frequently occurring at the extreme base. Colour. Red when fresh, become 
very dark on drying. Anatomy. Articulations variable in length, as much 
as eight times their breadth in the main branches, becoming shorter in the 
upper parts and scarcely twice as long as broad in the ramuli. Filaments 
slightly swollen at the junction of the articulations with each other. 
Attachment organ. Young plant attached by two or more rhizoids developed 
by longitudinal proliferation of pericentral siphons; other rhizoids occur 
later on the main axis and on procumbent branches, being formed by lateral 
proliferation of the siphons. A tendency to deep lobing of the expanded 
portion of the rhizoid frequently visible. Reproductive organs. Tetraspores 
interealary in development, borne iu distorted ramuli. Antheridia elongated 
