Marine Algce of the Orkney Islands. 303 



the island of Stronsay generally, according to Mr James 

 Cursiter ; Eousay (especially between Broch and Providence 

 Gjio), but the north shore, which has not been worked, 

 looks promising ; Carness Bay ; west side of Scapa Bay ; 

 Deerness ; Howquoy Head ; Burray (at Water Sound) ; Hoy 

 Sound, from Stromness to Breckness, in pools ; and Skaill 

 Bay, West Mainland. 



The dates given for the fructification and duration of the 

 species are necessarily approximate in many cases, varying 

 as they do with the locality, as well as with the chmatic 

 influences of different years. 



The classification adopted is that of Mr Edward Batters 

 in his excellent work, recently pubhshed, on the Marine 

 Algas of Berwick-on-Tweed. 



Class L— OYANOPHYCE^. 

 Order L— SCHIZOPHYCE^. 



FAMILY.— CHEOOCOCCACEtE. 



DEE,MOCAE,PA(Crn.), Bomet. 



1. Dermocarpa prasina (Reinsch), Bornet. 



At Scapa Bay, epiphytic on Polysiphonia fastigiata. Fruit in 

 winter. (G. W. T. 1887.) Xew to Orkney. 



Family.— NOSTOCHINE^. 



Tribe. — Eivularie j:. 



RIVXTLABIA, Roth. 



2. B-ivularia atra, Roth. 



On rocks and stones, also epiphytic on SpJiacelaria cirrliosa, 

 CoralUna officinalis, &c., in pools at Carness, opposite Hellyar 

 Holm. At all seasons. 



CALOTHHIX, kg. 



Calcthrix confervicola (Dillw.), Ag. 



In pools, Bay of Carness, opposite Hellyar Holm, very fine, 

 epiphytic on Sphacelaria cijrhosa. Always submerged. Annual. 

 Summer and autumn. 



