12() KJELLMAX, THE ALG^ OF THE ARCTIC SEA. 



Polysiphonia nigrescens (Huds.) Harv. 



Brit. Fl. 3, p. 332. Conferva nigrescens Huds. Engl. Bot. t. 1717. 



f. pectinata Ag. 



Hutchinsia nigrescens /? pectinata Ag. Syst. Alg. p. 151. 

 Descr. Polysiphonia nigrescens a pectinata J. G. Ag. Spec. Alg. 2, p. 1058. 

 Fig. Conferva nigrescens Engl. Bot. t. 1717. 



Exsicc. Polysiphonia Brodisei Aresch. Alg. Scand. exsicc. N:o 63 et 152. 

 » nigrescens » » » » N:o 62 et 304. 



f. protensa J. G. Ag. 

 Spec. Alg. 2, p. 1058. 



/i gracilis nob. 

 f. setacea, circa 10 cm. alta, fragilis, dilute violacea, fastigiato-ramosa. 

 Syn. Conferva atrorubens Wg. F1. Lapp, p. 511; fide herb. 

 Polysiphonia nigrescens Aresch. Phyc. Scand. p. 271. 

 » I) Dickie, Alg. Sutherl. 1, p. 142. 



» » Gobi, Algenfl. Weiss. Meer. p. 29. 



« » Nyl. et Seel. Herb. Fenn. p. 74. 



1) » Kleen, Nordl. Alg. p. 13. 



Khodomela gracilis » » » » 12. 



Remark on the synonomy. In his work on the algte of Nordlanden, Kleen records 

 RJiodomela gracilis as found in a little lake with almost fresh water called Kosinovandet. 

 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 Kleen has meant by his Rh. gracilis, is no 

 Rhodomela, however, but a peculiar form of Polysiphonia nigrescens that approaches 

 most nearly J. G. Agardh's f. protensa, although differing from it rather considerably. 

 I have called it above Rh. 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 Dickie 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. 



Geogr. 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 Dickie it has been collected in Baffin Bay much farther 

 to the north, viz. in Whale Sound at 77° N. Lat, but here it was found washed ashore. 



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