Diatoms. 



209 



IMeurosijjma \V. Sm. 

 a. Eupleurosignia. Stria- in three directions (transverse and oblique). 



P. nubecula W. Sm. 



W. Sm. Brit. Dint. [. p. 64, pi. 21, f. 201. 



var. subreeta I i 



Cl. Synops. Navic. Diat. I. p. 35. Pleurosigmct s. Cl. in Cl. et Grun. Arct. 

 Diat. p. 53. pi. 3, I'. 72. 



Very rare: Stamsund, r. 254 \>. x 21 jjl; oblique striae 18 

 on 1() |i, angle more than no", transverse stria' indistinct. Raphe 



central, almost straight. Somewhat broader in the middle, with 

 obtuse ends. 



Distribution (of the variety): Finmark. Greenland. Sea of 

 Kara. Balearic Islands. 



P. elongatnm \V. Sm. 



\V. Sm. Brit. Diat. I, pi. 20, l'. 199. Peragallo Monogr. Pleuros. pi. II, figs. 20— 21. 



Very rare: The 0stnesfiord r. 



Distribution: Coasts of the North Sea and Ireland. Baltic. 

 Arctic regions. The Mediterranean. Caspian Sea. North America, 

 east coast. Pacific Ocean. Indian Ocean. 



P. rigidtun \V. Sm. 



\V. Sm. Brit. Diat. I, p. Ii4. pi. 20, f. 19s. Pf.ragai.lo 1. .'. pi. VI. figs. 4—6. 



Very rare: Stamsund r, Gaukvsero r. 



Distribution: Coasts of the North Sea. The Mediterranean. 

 Red Sea, Indian Ocean. Pacific Ocean. West Indies. Straits of 

 Magellan. 



P. Noruianni Ralfs. 



Kalis in Pkitch. Inf. p. 919. /. affine Grun. in Cl. et Grot. Arct. Diat. p. 



51. Van Heurck Synops. pi. 18, f. 9. 



Frequent: Stamsund r. Svolvter c. the 0stnesfiord + c, Stene c, 

 Gaukvsero +• 



Distribution: Coasts of the North Sea. The Mediterranean. 

 Spitsbergen. Davis' Strait. East coast of North America. Pacific 

 Ocean. The Red Sea. 



P. strigotrnm W. Sm. 



W. Sm. Brit. Diat. I, p. 64, pi. 21. f. 203; pi. 23. f. 203. I'erag. 1. c. pi. V, figs. 1—2. 



Very rare: Stamsund r, Svolvser r. 



Distribution: Coasts of the North Sea. The Mediterranean. In- 

 dian Ocean. Africa. America. 



P. forniosum \V. Sm. 



W. Sm. Brit. Diat. I, p. 63. pi. 20, B. 195. Van Hei-rck Synops. p. llii. 



pl. 19. f. 4. 



Rare: Stamsund r, Stene r, Gaukva?ro r. 



Distribution : Coasts of the North Sea and Western Europe. 

 The Mediterranean. The Red Sea. Indian Ocean. Pacific Ocean. 

 West Indies. 



P. speciosiun W. Sm. 



W. Sm. Brit. Diat. I, p. 63, pl. 20, f. 197. Perag. 1. c. pl. II, Bgs. 13 — 16. 



Very rare: Stene, r. 



Distribution: Coasts of the North Sea. The Mediterranean. 

 Indian Ocean. Pacific < Icean. West Indies. 



b. Gyrosigma 1 1 1 



P. attenuatum (Kutz.) vy. Sm. 



W. Sm. Brit. Diat. I. p. 68, pl. 22. f. 216. 



var. scalp rum Gaill. et Turp. 

 Gaill. et Tim'. Mem. an Mus. XV, pl. X, XI. f. 3. P. acuminatum w. Sm, 



Brit. Diat. I, p. 116, pl. 21. f. 209. 



Very rare: The 0stnesfiord, r. 



Distribution (of the variety): North Sea, brackish and marine. 



P. baltiaun (Ehrb.) W. Sm. 



\V. Sm. Brit. Diat. I. p. 66, pl. 22. f. 207. Namcula o. Ehrb. Abh. Berl. 



Ak. 1830. p . 114. 



Very rare: Stamsund r, Svolvser rr. 



Distribution: Cosmopolitan in warm and temperate regions. 



Rlifticosigma (Dun, Per. 



R. areticum Cl. 



Cl. Diat. Arct. Sea p. 18, pl. Ill, f. 16. Peragallo Mon. Pleur. pl. X, figs. 

 16 — 17. Gyrosigma <*. Cl Synops. Navic. Diat. I. |i 119. 



Frequent: Stamsund r, the 0stnesfiord |- c, Gaukvsero c. 

 Distribution: Scotland. West coast of Norway, frequent. 

 Arctic regions. 



Seoliotropis Cl. 



S. latestriata (Breb.) Cl. 



Cl. Synops. Navic. Diat. I, p. 72. Amphiproia I. Breb. in Kutz. Sp. Alg. p. 93. 



Scoliopleura !. Grun. in Van Heurck Synops. pl. 17. f. 12. 



Very rare: Stamsund r. Stene r. 



Distribution: Coasts of the North Sea and Western Europe. 

 Caspian Sea. East coast of North America. West Indies. Cali- 

 fornia. 



Scoiiopli-iirn tumida (Breb.) Rabenh. 



Eabenh. Fl. Eur. Alg. p. 229. Van Hecrck Synops. p. 112. pl. 17, tigs. 11, 13. 



Navicula t. Breb. in Kutz. Sp. Alg. p. 77; Cl. 1. c. p. 155. 



Very rare: Gaukvsero, r. 



Distribution: Coasts of the North Sea and Western Europe. 

 Franz Josef's Land. Black Sea. Ceylon. Sidney. 



P«eii«loaiii|>lii|>roi'a Cl. 



Cl. Synops. of Navic. Diat. I. p. 71. 



According to Cleve the following species has 2 ehromato- 

 phores peculiar in shape and position. 



P. stauroptera (Bail.) Cl. 

 Cl. 1. c. Amphora stauroptera Bail. Smiths. Contrib. VII. p. 8, figs. 14 — 15. 

 Amphiprora obtusa Greg. Diat. of Clyde p. 506. pl. XII, f. 60 and f. 59 c („Amphi- 

 prora lepidoptera" Greg., non f. 59 a, b.). A. Schm. Nortls. Diat. pl. Ill, f. 1. 



Very rare: Stamsund r, the Ostnestiord r. 

 Distribution: North Sea. Finmark. Sea of Kara. Nova 

 Scotia. Sidney. (Cl. 1. c). 



27 



