THE GENUS POLYSIPHONIA. 289 
later, which bear dises or branch-like structures at their apices. The contents 
of the rhizoid pass into the branches, but no wall is formed. Reproductive 
organs. Tetraspores borne in the upper parts of the ramuli, usually extending 
to the tip. Antheridia elongated, narrow, and stalked, borne on the tips of 
lateral ramuli. Cystocarps shortly stalked, elongated, borne on the upper 
branches and ramuli. 
There seems to be no adequate reason for putting P. formosa Suhr into a 
separate species. J. G. Agardh, Sp. Alg. ii. p. 971, and Batters (9) p. 79 
regard P. formosa Suhr as a variety of P. urceolata (Lightf.), and this 
appears to be the maximum amount of separation which is justifiable. 
P. formosa Suhr has longer articulations than P. urceolata (Lightf.), and is 
more gelatinous when young. P. urceolata (Lightf.) is usually considered 
to be an annual, appearing in summer, but specimens occur at Kew, 
collected by Mrs. Griffiths, in which the base of the branches are clothed with 
a few broken ramuli, large tufts occurring at the top. This is evidently due 
to the lower branches having existed through the winter, and then in spring 
thrown off tufts of fresh ramuli. The same phenomenon has been observed 
in specimens obtained from Plymouth. Specimens obtained from the Nothe 
Pools, Weymouth (leg. A. D. Cotton, 1908) were pale pink when fresh, but 
became very dark in drying. The plants were 6:5 cms. in height, and the 
articulations of the main branches rather shorter than is typical for the 
species. 
Habitat. Oceurring on rocks, limpet shells, and large alge, particularly 
Laminaria, near low-water mark. Common. 
British Records. Scotland, Northumberland, Durham, Yorkshire, Norfolk, 
Kent, Sussex, Hants, Dorset, Devon, Cornwall, Cheshire, Isle of Man, Wales, 
Ireland, and the Channel Islands. 
Distribution in Europe. Atlantic shores of Northern Europe. 
B. More than four primary pericentral siphons. 
1. P. ATRO-RUBESCENS Grev. Flora Edinensis, 1824, p. 308. 
P. Agardhiana Grev. Scot. Crypt. Flora, iv. 1826, p. 210. 
Conferva atro-rubescens Dillw. Brit. Conf, 1809, pl. 70. 
C. nigra Hudson, Flora Anglica, 1798, p. 595. 
P. discolor (Ag.) Kütz. Spec. Alg. 1849, p. 825. 
P. nigra Batt. Catal. Brit. Mar. Alg. 1902, p. 51. 
References. Agardh (2) ii. p. 1085 et seg. ; De Toni (22) iv. p. 938; 
Hauck (31) p. 243. 
Icones. Greville, Scot. Crypt. Flora, l.e. Dillwyn, Brit. Conf. l e. 
Harvey, Phye. Brit. pl. 172. syn. 125. Kützing, Tab. Phye. xiii. 
1863, p. 26, tab. 82 (d-g).  Exsiccater. Desmaziéres, exs. no. 1205, 1842. 
Crouan, Alg. mar. Finist. no. 309, 1852. Lloyd, Alg. Ouest Fr. no, 16, 
1854. Wyatt, Alg. Damnon. no. 134. 
LINN. JOURN,—BOTANY, VOL. XLVI. Y 
