Diatoms. 



201 



B. Weissei (Grun.) '. 

 Triceratium Weissei Grun. in A. Schmidt Atlas pi. 95. t. 2. 



A specimen very similar to the figure referred to (from Arch- 

 angel) was found: Stene, rr (a single specimen). Rather coarse 

 radiating structure of puncta (pearls); about 6 rows on L0 ;.'.. Large 

 circular central space without puncta, only one or two near the 

 periphery. Side of the triangle ol ;>.. 



Might also belong to the genus Trinacria. I have not seen 

 a side view of the valve. 



Distribution: Only known fossil (Simbirsk, Archangel). 



Islliuiia Ag. 



I. enerris Ehrb. 

 Ehrb. Inf. p. 209. pi. 16, f. 6. Van Heurck Synops. pi. 90 figs. 1—3. 



Rather frequent: Moskenstrommen rr. Stamsund r, Svolvaer r, 

 Raftsund r, Brettesnes— Skroven r, Stene r. More frequent on algse. 



Distribution: Coast of Western Europe. Finmark: Spitsbergen 

 (Cleve). West Indies; Honduras. 



I. nervosa KiiTz. 

 Kutz. Bacill. p. 137, pi. 19, f. 5. Van Heurck Trait<5 rt. Hint. 152, pi. 34, f. 891. 



Very rare: Raftsund r. 



Distribution: Western Europe. Denmark. Arctic regions. 

 Honduras: San Francisko. Kerguelen. 



6. Chsetocerese. 



Kaclci iastrum varians Laid. 

 Laud. Trans. Micr. Soc. 1863, XII, p. 8, pi. Ill, figs. 1-6. 



Derived from the plankton. 



Very rare: Stene rr. 



Distribution: Neritic plankton species, from the western coasts 

 of Europe. Warmer coasts of the Atlantic, Indian and Pacific 

 Oceans. Rare off the west coast of Norway. 



Clisetoceros Ehrb. 

 C. atlanticns Cl. 



Cf. above p. 100. 



Derived from the plankton. 



Very rare: Gaukvcero r. 



C. contortits Schutt. 



Cf. above p. 101. 



Thickened horns, most probably belonging to this species, is 

 found now and then in the bottom samples, though seldom. Un- 

 doubtedly derived from the plankton. 



C. diadema (Ehrb ) Schutt. 



The characteristic resting spores of this species (Syndendriwm 

 diadema Ehrb.) occur rarely: 



Stamsund r, Svolvaer r, Gaukva?ro r. Derived from the plankton. 



Distribution: Cfr. above p. 101. Syndendrium diadema Ehrb. 

 also in Peru <raano. 



St<i>hanogonia Ehrb. 



A specimen very similar to S. actinoptychus (Ehrb.) Grun. 

 in Van Heubck Synops. p. 83a, figs. 2 — 4 was found in the sample 

 from Moskenstrommen. 



Nearly circular. Diameter 70 ;i.. 15 radii. On the smaller 

 upper disc, a coarse spine seems to be found. In other respects 

 corresponds very well to the figure referred to. 



Stephanogonia polygona Eheb. seems to be a similar form, 

 perhaps the same. Both are probably resting spores (cfr. Schutt 

 in Engleb and Pkantl, Xatiirl. Pflanzenf., 'I'll. 1, Abth. 1 b, 

 p. 147). 



Distribution: I loth species mentioned are known from ,, North 

 America" (Ehrenberg). The figure mentioned represents a fossil 

 specimen from Nottingham deposit. 



Pyxilla baltica Grun. 

 A. Shim. Nords. Diat. pi. 3, f. 25. Van Heurck Synops. pi. S3, f. 2 



According to the figure in Henscii (5ter Her. Konnn. Kiel, 

 pi. V. f. 38 e) l J //.'ill<i baltica must be the resting spore (endoeyst) 

 of Rhizosolenia setigera Brightw. 



Undoubtedly derived from the plankton. 



Very rare: Bhizosolenia setigera is a neritic plankton diatom 

 from the coasts of Europe (Western I-;.. Skagerak, Mediterranean). 

 Pacific Ocean. Indian Ocean; north of South America. • Pyxilla 

 baltica is known from the Baltic, and fossil from Simbirsk. 



II. Pennatse Schutt. 



7. Synedrese. 

 Synod ra. 



a. Eusynedra V. H. 



S. affinis Kxtz. 

 Kutz. Bacill.. p. us. )il. 15, 6gs. 6. 11. Van Heurck Synops. pi. 41. f. 13. 



var. tabiilata (Kutz.) V. H. 

 V. II. Synops. pi. 41, f. 9 a. Synedra I. Kctz. 



Very rare: Svolvaer r, Ostnestiord r. 



Distribution: Frequent on the coasts of Europe. Arctic- 

 regions. 



S. kamtschatica <Jrun. 

 Grun. in Cl. et grun. Arkt. Diat. p. 106, pi. VI. 



var. intermedia Grun. 1. c. 1'. 111. 



Very rare: Stamsund r. 



Distribution: Kamtschatka, Finmark, Spitsbergen, Greenland, 

 Kara Sea, East Cape. 



S. iihm (Nitzsch.) Ehrb. 

 Van Hri i;f k Synopsis pi. 38, f. 7. 



Fresh water species. 



Very rare: Svolv;er r. 



Distribution: Common fresh water species. 



26 



