332 Mr George Traill on the 



which is new to Britain. Several specimens in Mr Pollexfen's col- 

 lection from Skaill have lately been examined by Mr Batters, and 

 he pronounces them to be this variety also. 



203. Rhodomela subfusca (Wood.), Ag. 



Common on rocks and stones in pools between tide marks. 

 Perennial. Tetraspores in swollen ultimate ramuli in summer ; in 

 stichidia in winter. 



POLYSIPHONIA, Grev. 



204. Polysiphonia xirceolata (Lightf. ), Grev. 



On rocks, and epiphytic on Alf^ge, between tide marks ; especially 

 in pools. Usual duration from March to October, but plants some- 

 times last through the winter. Fruit in July and August. Scapa, 

 fine ; Hoy Sound ; West Mainland, as at Skaill Bay ; Kousay, &c. 

 The vars. ^Jrt^e?J6^ and formosa also occur. 



205. Polysiphonia roseola (Ag. ), Aresch. 



Epiphytic on Ulva Laduca, Linn., in the "Peerie Sea," Kirkwall. 

 Identified by Kjellman as young plants of Polysiphonia rospola, 

 which species is probably new to Britain. July 1887 (G. W. T.) 



206. Polysiphonia fibrata (Dillw. ), Harv. 



On damp exposed rocks, and epiphytic on Algse, in the shade, a 

 little below half-tide level ; also in pools, but less commonly. 

 Usually left uncovered by the tide for some hours daily. Annual. 

 Summer and autumn. Fruit from June to September inclusive. 

 Papa-Westray, in pools ; fine at " Ting of the Dyke," Scapa ; 

 Birstane Bay, &c., common. 



207. Polysiphonia violacea (Ag.), Wyatt. 



On rocks and stones, and epiphytic on several of the smaller 

 AlgiB, near low- water mark. Annual. Hunda Sound; Water 

 Sound, Burray, fine (J, W. Gray), 



208. Polysiphonia fibrillosa (Dillw.), Grev. 



On rocks, and epiphytic on Polyides rotundus, Cladostephus 

 spongiosus, &c., in clear sunny pools at about half-tide level. 

 Perennial. Fruit in July, August, and September. Lingro, Scapa ; 

 Bay of Carness, in pools, &c. 



209. Polysiphonia Brodiaei (Dillw. ), Grev. 



On rocks, and parasitic on Algaj, in pools near low-water mark. 

 Annual. May to September. Fruit in July and August. Skaill 

 Bay, West Mainland ; Scapa ; Kirkwall Bay, opposite Iceland 

 Skerry, &c. 



210. Polysiphonia elongella, Harv. 



On shells and stones in deep water. Biennial. Spring and 

 summer. Calf Sound, 4 fathoms, coral bottom. Found also in 

 Kirkwall Bay. 



