KONGL. SV. VET. AKADEMIENS HANDLINGAK. BAND. 20. N:0 5. 171 



Phyc. Brit. This must be the form recorded by J. G. Ag. under the combined names 

 of C. rubrum t] pedicellatum. It seems to be easy to recognize by having luimerous, 

 but short and not dichotomously compound lateral branches. This form leads över to 

 f. prolifera with its more or less richly proliticating thallus. Some of the specimens 

 from the Polar Sea, that I have seen, are raost nearl}^ related to the Ceramium secumlatum 

 figured by Lyngbye, others to Harvey's C. botrycarpum. Of all the arctic forms that 

 one which I have had delineated in table 15 fig. 7, is perhaps the most peculiar. I 

 have thought to recognize in it a form of C. rubrum described by Harvey under the 

 name of f. squarrosa. It is a small-sized, rather slender form, most easily recognizable 

 by the upper segments being strongly spreading from one another, those of the last 

 order, which bear tetrasporangia, being recurvate. 



Habitat. In the Norwegian Polar Sea this alga is mostly litoral, in the other 

 parts of the Polar Sea that I have myself examined, it is sublitoral, belonging here to 

 the Laminariacai-formation. It is generally attached to other alga3, growing scattered on 

 exposed coasts, and more abundant in sheltered localities. At Nordlanden it has been 

 found with sporocarps and tetrasporangia during all summer, at Spitzbergen with tetra- 

 sporangia at the end of July and the beginning of August. At Novaya Zemlya and 

 Waygats in June and July, and at Finmarken in July, August, and September, I have 

 met with only sterile individuals. At Russian Lapland, on the coast of Cisuralian Samoyede- 

 land, and in the White Sea, it appears often to bear plenty of tetrasporangia in summer. 



Geogr. Distrib. It belongs to the Atlantic as well as the arctic region of the 

 Polar Sea, reaching its maximum of frequency within the southern part of the former 

 and not being widely spread within the latter. Its northernmost known place of growth 

 is on the west coast of Spitzbergen about Lat. N. 76° 30'. 



Localities: The Norweffian Polar Sea: Nordlanden, common and plentiful; Fin- 

 marken, pretty local and scanty at Gjesva^r and Talvik. 



The Greenland Sea: the west coast of Spitzbergen, generally local and scanty, in 

 one place abundant. 



The Murman Sea: the coast of Russian Lapland and Cisuralian Samoyede-land; 

 Kolgujew Isle; the west coast of Novaya Zemlya and Waygats, from M. Karmakul Bay 

 to Jugor Shar, local and scarce. 



Baffin Bay: the west coast of Greenland: Neuherrnhut, Godhavn. 



At Nordlanden all the. forms mentioned are to be found. North of this region 

 only f. decurrens and f. genuina are met with, most commonly the former or transitions 

 between this and the typicai form. 



Ceramium acanthonotum Carm. 

 in J. G. Ag. Advers. p. 26. 



f. typiea. 



Desor. Cerainium acaiitlioiiotura J. G. Ag. Epicr. p. 103. 

 Fig. » )> Habv. Phyc. Brit. i. 140. 



Exsicc. » » Aresch. Alg. Scand. exsicc. N:o 12. 



