i 
_ 
KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 20. N:0 5. 119 
Gost on this point follows the example of J. G. Acarpu. However, these two plants 
cannot possibly be identified, because they differ essentially in structure from each other. 
Polysiphona pulvinata J. G. AG. and Gost, according to both authors, has 
4-siphonic articles, whereas Arescnouc’s P. pulvinata in Phyc. Scand. is 6-siphonie. 
He says expressly »Interstitia sub microscopio visa tristriata»> and the specimens distri- 
buted by him in Alg. Scand. exsice. Ser. 1. N:o 60, to which he refers, possess indeed 
6-siphonic articles. The same plant has been distributed by him afterwards in the 
second series of this work of exsiccate N:o 67. This is quoted by Gopr as identical 
with his P.- pulvinata from the White Sea. All the specimens of that P. pulvinata of 
ArescuouG, which | have had an opportunity of examining, have 6 pericentral siphons, 
differing thereby from the P. pulvinata Gost found in the White Sea. That this struc- 
ture is an essential characteristic of P. pulvinata Arescu., is evident by this author's 
detailed description of it in Obs. Phyc. 3. p. 7—8, where it stands under the name 
of P. hemispherica Arescu., Syn. P. pulvinata Arescu. Phyc. Scand. p. 57, Alg. Scand. 
exsicc. Ed. I. N:o 60 and Ed. II. N:o 67. I dare not allege with certainty that P. 
pulvinata J. G. Ac. does not occur on the coast of Scandinavia. ArescnouG neither 
records it in Phye. Scand. nor did he mention it as Scandinavian in his public lectures 
on the alge of Scandinavia delivered some years ago. I have myself never seen any 
plant, neither at Bohusléin nor on the coast of Norway, that might be identified with 
P. pulvinata J. G. Ac. But on the other hand I have found at several times on the 
west coast of Scandinavia a Polysiphonia much resembling in habit P. pulvinata i. e. 
P. hemispherica Arescu. 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. wrceolata. I think it is a P. urceolata of this kind from the Polar Sea 
that Gopr has seen and determined as P. pulvinata J. G. Ac. This seems to be indi- 
cated, besides by Gosrs decided statement as to its having 4 pericentral siphons, by the 
fact of its constituting »z2emlich dichte Biischeb — P. pulvinata J. G. Ac. is densely 
tufted — and of such an experienced algologist as Ruprecur having called it 2. ro- 
seola Ac. Cp. Gost 1. c. p. 26, note. P. stricta Croat vide P. arctica. 
Habitat. 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 alge sometimes to 
stones, and seems to prefer an exposed coast. For although it penetrates also into the 
interior 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 Kirn 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. 
