No. 3] REMARKS ON NORTHERN LITHOTHAMNIA. 101 



question is growing, I will mention Chcetomorpha sp. from Porto 

 Rico (Howe!) The cells are here a little smaller, and the con- 

 ceptacles are a little lower than usual. It, therefore, some- 

 what approaches M. Lejolisii, but as it bears heterocysts, it 

 must be referred to M. farinosa. Therefore, I think it likely 

 that the M. confervicola from Guadeloupe admitted by Mssrs. 

 Maze and Schram 1 ) and Mr. Murray 2 ) also belongs to this 

 species. 



The species seems mostly to occur in the upper part of the 

 sublitoral region and to prefer localities fairly sheltered. It bears 

 reproductive organs during the whole of the year. 



Area: The typical form of the species is distributed in boreal 

 and tropical areas : On the Atlantic coast of Europe as far to the 

 north as Cherbourg and the southern part of the British Isles 3 ); 

 the Mediterranean and the Adriatic ; on the Atlantic coast of North 

 America as far to the north as Wood's Holl, Mass. Its occurrence 

 southward in the South Atlantic is not exactly known. It also 

 occurs in the Red Sea, and in the Indian and the Pacific Oceans 

 it is widely dispersed, especially in the former, e. g. on the East 

 coast of Africa, at Mauritius, in the Gulf of Siam, in the Malayan 

 archipelago. But specimens typically developed are not yet known 

 from the Pacific coasts of America, and its northern and southern 

 limits here are at present uncertain. 



The form borealis is only known from Roundstone on the 

 West coast of Ireland (!); Denmark: Nykobing Mors (Rosen- 



*) Maze et Schram. Essai de classification des Algues de la Guadeloupe. 

 Basse Terre 1870—1877. 



2 ) George Murray. Catalogue of the Marine Alga? of the West Indian 

 Region. Journal of Botany 1888—1889. Pag. 21. 



3 ) The distribution to the north along the British Isles is unknown to me. It 

 is recorded by Batters, Catal. of Brit. Mar. Alg. (1902), p. 96, as being 

 not uncommon on the coasts of the British Isles. It seems doubtful to me 

 that the alga should occur even as far to the north as to the north of 

 Scotland. On the other hand, it is possible that f. typica appears as far 

 to the north as on the coasts of Denmark and on the south coast of 

 Norway. It does not, however, occur among the large material I have 

 examined from Denmark, so that it is likely to be here contingently of rare 

 occurrence. 



