1 96 



E. Jørgens 



specimen agrees completely with Coscino.sira pob/chorda Gran, but 

 wants the peculiar transverse processus of the latter species. 



Such forms, which are perhaps solitary cells of Coscinosira, 

 may easily be mistaken for C. lineahts. 



Distrihidion: The main species is cosmopolitan. Cleve and 

 OsTRUP mention C. Uneahia from several arctic localities: Finmark, 

 iiaren Eiland, Greenland, Spitzbergen, Kara. I should, however, 

 think that the species has been confounded with Coscinosira polij- 

 rhoriln, at any rate to some extent. 



C. excentricns Ehrb. 



Cf. above p. 92. 



Fi'equent: Moskenstrømmen r, Stamsund +, Graukva^i'o i' -\-. 

 Derived undoubtedly from the plankton. 

 Distribution : Cosmopolitan. 



C. Kiitziugii A. Scum. 

 A. ScHM. Atlas, pi. 57, f. 17. C. maryivatus A. Schm. Novels. Diat. pi. .3, f. 35- 



As Gkunow remarks, this species is intermediate between t'. 

 excentricns and the difficult group of C. snhtilis. 



Very rare: Raftsund r, Stamsund r. 



Distribution: North Sea. Arctic and antarctic regions (Grun.). 

 Not mentioned by Cleve as arctic. Very nearly related forms 

 are found near Greenland (C adnmhruttis Østr.) and Jan Mayen 

 I L898, E. Jørgensen). 



C. Rothii (Ehrb.O Gein. 



Gru.n'. Diat. Franz Jos. Land, p. 29, pl. III (C), fius. 20 a, b, 22. C. si/mme- 



tricus A. Schm. Atlas pl. 57, tigs. 25 — 27, non Gbev. Heterostepliaiiici Botltii 



Eheb. a octovaria Mikrogeolouie 35 A, XIII B, fig. 4 a. 



Belongs to the difficult group of C. subtilis Ehrb., as well as 

 tlie following spedes and a good many more, which probably will 

 not bear a more thorough examination. 



Structure plainly fasciculate, with numerous fasciculi separated 

 by radial lines made conspicuous by the marked inner ends of the 

 l)eginnings of new rows. Small marginal apiculi in the middle of 

 the fasciculi, one in each. Valve almost flat (occasionally undula- 

 ted according to Grunow). 



Very rare: Stamsund r, Raftsund r. lirettesnes— Skroven r. 

 Probably a plankton form. 



Distribution: P)elgium, Scotland; Caspian Sea. Warmer re- 

 gions of America and Asia. Southern Seas. 



C. Norinanni (innG. 



C.REO. Quart. .louni. Micr. Sc. 1859, p. HO, pl. 6, fig. 3. C. „noriiianmis" Van 



Heuhck Synops, pl. 131, I. C', fascicitlatns A. Schm. Nords. Diat. pl. 111, figs. 



41, 42: Atlas pl. .57, figs. 9, 10. 



\'ery clo.scly related to tlio preceding species. Differs in hav- 

 ing a distinctly convex valve, liner structure (though variahlc in 

 this respect), more numci'ous anil narrow fasciculi and less distinct 

 marginal apiculi. 



It is ]icrliii])s not quilo cci-tain lli;it tins species is identical 

 with ('. Xoniiiiuiti (liiEd.; the nanu^ ('. /u.-nrtilnliis A. Scnm. (1874) 

 must however be abolished on account of <'. fusviruliitas O'Mhak.v 

 (ISCT). 



'J'his species seems to me to answer tolei'ably well to C. pune- 

 lidatus Greg. In specimens with fine structure the fasciculi are 

 only seen with difficulty, while the clear, scattered dots mentioned 



by Geegoky 1. c. are conspicuous. If this should prove correct, 

 the C. Xormanni Greg, is perhaps the same as C. Rothii Grun. 



Rather frequent: Stamsund r 4-, Svolvær r -f, Brettesnes— 

 Skroven r, Østnesfiord r +, Stcno r. Probably a plankton species 

 (living or fossil). 



Distribution: Western Europe. America. Arafura Sea. 



C. ciirvatulus Gruk. 



Cf. above p. 92. 



Derived undoubtedly from the plankton. 

 Very rare: Stene rr. 



Distribution: Arctic regions; Northern European coasts; Ba- 

 learic Islands. America and Africa. 



C. stellaris Rop. 



Cf. above p. 92. 



Derived undoubtedly from the plankton. 

 Very rare : Gaukværø r. When the conspicuous star is want- 

 ing, the species is difficult to determine. 



var. symholophorus (Grun.). 

 C. symhohjyhorus Grun. Diat. Franz Jos. Land, p. 82, pi. IV (D), figs. 3— (j- 



Differs from the main species in having much coarser structure. 



Very rare: Moskenstrømmen r, Raftsund r. Like the main 

 species planktonic. 



Distribution: The main species occurs in Western Europe, the 

 Mediterranean and the antarctic regions, the variety in the arctic 

 and antarctic regions. 



C. concitinus W. Sm. 



Cf. above p. 9:3. 



Derived undoubtedly from the plankton. 

 Very rare: Gaukværø, rr; Stene, r. 

 Distribution : Cosmopolitan. 



C. vcntnilis Kiihb., Rattr. 



Cf. above p. 9:5. 



Derived pi'obably from the plankton. 



Not unfrciiuent: Moskenstronnucn r. Stamsund i', Raftsund r. 

 Stene r. 



Distiiliutiou : Cosmopolitan. 



C. siibbnlJiens Jørg. 

 C', octdus iridis ancf. scaiid., p. p. 



Cf. above ]>. 9 1. 



Probably dcrivcil tVoin tlu' plankton. 



Rare: Moskenstrømmen r, Kaflsnnd r. (iaukv;erø r -|-. 



Distribution: Arctic regions. 



Hail. Anieric. Jdurn. Sc. 185(1, p. :i. A. SciiM. Atlas, pl. tiS, l'. 11. 



Vei'y rare: Raftsund, rr. Diamctor l;i.'3 [i. Coarse structure; 

 areoles increasing towards the border, at the centre S'/s) i^eai' t'le 

 border 2 on 10 |)-; the largest ones only little larger than those at the 

 very margin. Lai'ge and very conspicuous .,papillæ" (poroides). 



