KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 20. N:0 5. 119 



GoBi on this point follows the example of J. G. Agardh. However, these two plants 

 caimot possibly be identiiied, because they differ essentially in structure from each other. 



Polysiphonia pulvinata J. G. Ag. and Gobi, according to both authors, has 

 4-siphonic artides, whereas Areschoug's P. pidvinatn in Phyc. Scand. is 6-siphonic. 

 He says expressly »Interstitia sub microscopio visa tristriata» and the specimens distri- 

 buted by him in Alg. Scand. exsicc. Ser. 1. N:o 60, to which he refers, possess indeed 

 6-siphonic artides. The same plant has been distributed by him afterwards in the 

 second series of this vvork of exsiccatse N:o 67. This is quoted by Gobi as identical 

 with his P. pulvinata from the White Sea. All the specimens of that P. pulvinata of 

 Areschoug, which 1 have had an opportunity of examining, have 6 pericentral siphons, 

 differing thereby from the P. pulvinata Gobi found in the White Sea. That this struc- 

 ture is an essential characteristic of P. jndvmata Aeesch., is evident by this author's 

 detailed description of it in Obs. Phyc. 3. p. 7 — 8, where it stånds under the name 

 of P. hemisphceric.a Aresch., Syn. P. imlvinata Aresch. Phyc. Scand. p. 57, Alg. Scand. 

 exsicc. Ed. I. N:o 60 and Ed. H. N:o 67. I dåre not allege with certainty that P. 

 pulvinata J. G. Ag. does not occur on the coast of Scandinavia- Areschoug neither 

 records it in Phyc Scand. iior did he mention it as Scandinavian in his public lectures 

 on the alg» of Scandinavia delivered some years ago. I have myself never seen any 

 plant, neither a,t Bohuslän nor on the coast of Norway, that raight be identified with 

 P. pulvinata J. G. Ag. But on the other hand I have found at several times on the 

 west coast of Scandinavia a Poiysijjhonia much resembling in habit P. pulvinata i. e. 

 P. hemispha^rica Aresch. Like this, it forms very dense, nearly hemispherical tufts, 

 which assume a brownish colour in drying. Like this, it possesses a dense plexus ra- 

 dicalis, formed of the prostrate, intertwisted, lower parts of the frondal axes, which throw 

 out short, hyaline rhizines furnished at the top with a crenate, scutiform fastening- 

 disk. It is, however, always 4-siphonic and passes by plainly intermediate forms into 

 the typical P. urceolata. I think it is a P. urceolata of this kind from the Polar Sea 

 that Gobi has seen and determined as P. pulvinata J. G. Ag. This seems to be indi- 

 cated, besides by Gobi's decided statement as to its having 4 pericentral siphons, by the 

 fact of its constituting »ziemlich dichte BvscheU — P. pulvinata J. G. Ag. is densely 

 tufted — and of such an experienced algologist as Ruprecht having called it P. ro- 

 seola Ag. Cp. Gobi 1. c. p. 26, note. P. strida Croall vide P. arctica. 



Hahitat. The present plant is properly and usually litoral in the Polar Sea, but 

 it occurs also within the sublitoral zone, even descending to its lower limit. I have 

 taken it in Finmarken in 15 — 20 fathoms water, but it was usually met with in the 

 lower part of the litoral zone. It is fastened sometimes to other algas sometimes to 

 stones, and seems to prefer an exposed coast. For although it penetrates also into the 

 interiör of deep bays, it does not there, according to my experience, develop to the 

 same luxuriancy as in exposed localities. It grows scattered, though sometimes in 

 rather large numbers. According to Kleen it bears sporocarps and tetrasporangia 

 during the whole summer in the southern part of the Norwegian Polar Sea. On the 

 coast of Finmarken I have found specimens with such organs at the end of July and 

 the beginning of August. 



