310 K.JELLMAN, THE ALGJE OF THE ARCTIC SEA. 



Geogr. Distrib. It is known in the Polar Sea north of the Atlantic, occurring 

 in large nmnbers luxuriantly developed even at Spitzbergen. Its northernmost point is 

 Advent Bay on the west coast of Spitzbergen Lat. N. 78° 15'. 



Localities: The Norwegian Polar Sea: Nordlanden cornmon according to Kleen; 

 Finmarken, the south coast of Magerö abundant. 



The Greenland Sea: in the lagoons at Advent Bay on the west coast of Spitz- 

 bergen, abundant. 



The White Sea: Golaja-Koshka Isle. 



Rhizoclonium Pachydcrmum Kjellm. 

 Algenv. Murm. Meer. p. 55. 



f. typica. 

 Descr. et Fig. Rhizoclonium pacliydermum Kjellm. I. c. et t. 1, tig. 26 — 28. 



f. tenuis nob. 



f. quam f. typioa tenuior et ramosior; ramis caiiloideis 30 — 40 i.i. crassis, e cellulis iierabraiia teiiuiore 

 coiitextis, rhizoideis crebris. 



Remark on the forms of this species. In the herbarium of the Copenhagen Muse- 

 um there is a considerable quantity of Rhizodinium from Greenland coinciding so 

 closely with the Rli. pachydermuni from Novaya Zemlya described by me, that it can 

 hardly be regarded as specifically distinct from this. It is much branched, even more 

 so than the typical Rh. pachydermuni, with two sorts of branches, numerous rhizoid 

 branches, usually formed of more than three cells, and pretty scarce cauloid branches 

 that give rise to rhizoid branches and even to one or two cauloid branches of a 

 higher order. The sympodial main axis is much thicker than the secondary axes 

 and ends dowuAvards in an obovate cell with discoid expanded extremity. The cells 

 of the main axis have very thick, distinctly stratiform walls. It is chiefly distinguished 

 from the typical form by its cauloid branches being more slender, usually only 30 — 

 40 ,«. in diameter. Their cell-walls are somewhat thinner than in f. typica, although 

 even in f. tenuis, especially in the lower portions of the cauloid branches, they are 

 much thicker than in the majority of known Rhizoclonia. 



Hahitat. This species belongs to the litoral zone. At Novaya Zemlya I saw it 

 forming a thin stratum on rocks at high-water mark. I have afterwai-ds met with it 

 on the north coast of Sibiria in lagoons with somewhat brackish water, forming mats 

 lying loose on the bottom. 



Only sterile specimens have been observed. 



Geogr. Distrib. It seems to be widely distributed within the Arctic region, and 

 is probably circumpolar. The most northern place where it is known to occur is Kar- 

 makul Bay on the west coast of Novaya Zemlya, about Lat. N. 72° 30'. 



Localities: The Murman Sea: the west coast of Novaya Zemlya, scarce at Karma- 

 kul Bay. 



