126 KJELLMAN, THE ALGA! OF THE ARCTIC SEA. 
Polysiphonia nigrescens (Huns.) Harv. 
Brit. Fl. 3, p. 332. Conferva nigrescens Hups. Engl. Bot. t. 1717. 
f. pectinata Ag. 
Hutchinsia nigrescens # pectinata Ac. Syst. Alg. p. 151. 
Descr. Polysiphonia nigrescens a pectinata J. G. Ac. Spec. Alg. 2, p. 1058. 
Fig. Conferva nigrescens Engl. Bot. t. 1717. 
Exsice. Polysiphonia Brodizi Aruscu. Alg. Scand. exsice. N:o 63 et 152. 
» nigrescens » » » » N:o 62 et 304. 
f. protensa J. G. Ac. 
Spec. Alg. 2, p. 1058. 
( gracilis nob. 
f. setacea, circa LO em. alta, fragilis, dilute violacea, fastigiato-ramosa. 
Syn. Conferva atrorubens We. Fl. Lapp. p. 511; fide herb. 
Polysiphonia nigrescens ArwscH. Phye. Scand. p. 271. 
» » Dickie, Alg. Sutherl. 1, p. 142. 
» » Gost, Algenfl. Weiss. Meer. p. 29. 
D » Nyl. et Sel. Herb. Fenn. p. 74. 
» » KuEEN, Nordl. Alg. p. 13. 
Rhodomela gracilis » » » » 2: 
Remark on the synonomy. In his work on the algw of Nordlanden, KiEeen records 
Khodomela gracilis as found in a little lake with almost fresh water called Kosmovandet. 
There is indeed to be found in his collections a plant taken at this place, which 
approaches very nearly Rhodomela gracilis in habit, and there is no other alga of his 
that could by any possibility be called Rh. gracilis. This plant, which is accordingly, 
as far as I can see, precisely that which Kiren has meant by his Rh. gracilis, is no 
Rhodomela, however, but a peculiar form of Polysiphonia nigrescens that approaches 
most nearly J. G. AGarpn’s f. protensa, although differing from it rather considerably. 
I have called it above Fh. nigrescens f. protensa ~ gracilis. 
Habitat. The common form, f. pectinata, occurs on the coast of Norway in rock- 
pools within the litoral zone, in the White Sea in the sublitoral zone down to a depth 
of 18 fathoms, generally on sandy and pebbly bottom. According to Dicxm the plant 
has been brought up from a depth of 40—50 fathoms in Baffin Bay. Cp. above p. 11. 
It flourishes on exposed as well as sheltered parts of the coast, growing scattered. It 
has been found with tetrasporangia on the coast of Norway in July and August, in 
the White Sea at the middle of July. The form protensa gracilis is a brack-water 
form, as has been mentioned above. It is known only in sterile condition. 
Greogr. Distrib. The species belongs indeed to the Atlantic as well as the arctic 
region of the Polar Sea, but it has its maximum of frequency within the former re- 
gion, being but little distributed in the latter. It has assuredly immigrated from the 
south into the Arctic Sea proper. Its northernmost certain locality is the coast of 
Russian Lapland. According to Dickim it has been collected in Baftin Bay much farther 
to the north, viz. in Whale Sound at 77° N. Lat., but here it was found washed ashore. 
