if. AUlllilUltiuilU ((iREO.). 



Pinnularia A. (InEO. Diat. of Clyde p. 488, pi. IX, f. 21. Cocconeis quaritercnsis 



A. ScHM. Nords. Diat. pi. Ill, f. 1(5; Atlas pi. 192, flg.s. 20—24. Rhaphtnit'is 



q. CiRUN. Wien Verli. 1862, p. 381, pi. 7, f. 24. Xaiicula onilum A. Scum. 



Nords. Diat. pi. II, f. 12. Hefaoneis q. Cl. 1. c. ]>. 184. 



„Costæ apparently marginal, strong-, about -Jo in o.ooi", yivino- 

 the appearance of a narrow marginal band of very strong costæ. 

 Within this band, however, the valve, on close inspection, is found 

 to be marked with similar but much fainter costæ nearly to the 

 median line. Tlic valve appears to be thicker near the margin 

 than in the middle, and this perhaps is the reason why the costæ 

 are so strong and conspicuous there." Gkeg. 1. c. 



It seems to me that there can scarcely be any doubt that 

 Pinnularia Allmanniana Geeg. is synonymous to Cocconeit; qnnr- 

 nerensis Geun. Size, shape and sti-ucture agree very well in both 

 species. 



There seems to be a niarL;"inal rim whicii lias, liowevcr, only 

 faint traces of loculi. 



Rare: Stamsund r, Stene r. 



Dis-triliutio)i : Coasts of the North Sea. Arctic regions. The 

 Mediterranean. 



Cocconeis norvegica (iRUX., 

 A. SCHM. Nords. Diat. pi. Ill 



Upper valve as illustrated 1. c. by A. Schmidt. Instead of 

 the median line (pseudoraphe), there is often a linear blank space, 

 which sometimes (but rarely) is somewhat irregularly widened. The 

 lower valve has a very delicate structure, consisting of close, some- 

 what radiating striæ, in the median part of the valve coarser and 

 more conspicuous, about 15 on 10 [j-, otherwise very faint, about 

 20 on 10 |i. Raphe strait, extending to the margin; the inner 

 ends somewhat thickened, separated from each other. A rather 

 broad hyaline border, but no loculiferous rim. 



Cl. .Synops. Navic. Diat. II, p. 180 mentions that he has 

 found a frustule of Cocconeis hjru with an upper valve like that 

 illustrated by A. Schm. 1. c. (pi. Ill, f. 18, 1, upper figure). I 

 have, however, found a frustule, showing this upper valve, in con- 

 nection with a lower valve of the structure just described. There 

 must therefore here be some mistake, if there are not two different 

 species, with very similar upper valves. 



There is a marginal rim, like a somewhat broad hyaline border, 

 with only faint traces of loculi. 



Rare: Stamsund r-|- (many specimens); Stene r. 



Distribution: West coast of Norway (Solsvik near Bergen). 



I'oceoneis Eimn , Cl. 



Valves eeo.state, with a marginal loculiferous rim, dissimilar in 

 structure. 



C. scutelltim Ehkb. 

 14, f. 8. V.\N Heurck Syt 



l:i2, pi. 2St, tigs. 1—3. 



According to Cleve exceedingly variable. It seems, however, 

 that he has gone too far when referring so many different forms 

 to this species, as he has done (1. c. pp. 170—171). 



Not uiifrequent. in different forms wliich only l)adly answei- 



to the varieties described: Stuinsmid r, Svolvær i-, Ostiie.sliord i-, 

 Stene r. 



Dlstrlhidion : Cosmopolitan. 



C, distans fiREO., A. Schm. 



(iUEO. Diat. of Civil.-, p. 490, pi. IX, f. 2.3 (18.57, non Micr. .Journ. Ill, p. ;^9. 



pi. IV. f. <K 18.">.") «hirh (iREO. 1. c. p. 491 liiniself declares to be a var. of (. 



scutellum illustr.ited as C. distans by mistake). A. Schm. Nords. Dial. pi. Ill, 



fig's. 22—23 (forma minima Perao.). 



Small specimens, very well answering to the figures in A. Sch.m. 

 1. c. (f. 2.3 entire frustule) occurred. They had no loculiferous 

 rim, only a hyaline border. Lower valve with very faint and in- 

 distinct striæ. 



There is, however, sucji a remarkable agrceinenl with a foim 

 of 0. scutellum, most probably the one, mentioned above, which at 

 first was figured by Gkegoey as C', distans, that I do not feel 

 quite sure if not these two forms after all belong together. The 

 only difference seems to be the larger marginal areoles which are 

 wanting in the true C. distans. 



The variety of C', scutellum just mentioned differs remarkably 

 from the common forms. There is a nai-row marginal rim, but no 

 loculi. Lower valve with straight raphe, stretching to the margin. 

 Median pores somewhat separated from each other. Axial area 

 indistinct except towards the central nodule, where it suddenly di- 

 lates into a small, round, central one. Striæ finely radiating, much 

 curved towards the ends of the valve, most conspicuous near the 

 margin, distinctly punctate, about 14 on 10 |i. A narrow striate 

 border with striæ somewhat closer and less conspicuous than the 

 marginal striæ of the valve, 15 — 16 one 10 [l. 38 \>. x 29 [i. 



Smaller specimens seem to pass insensibly into such forms, 

 which A. Schm. has figured 1. c. 



Very rare: Stamsund r. 



Distrihution : Coasts of the North Sea. The Mediterranean. 

 Indian Ocean. Central and Arctic America. Sea of Kara. 



A. Schm. Nords 



C. lyra 



III. f. 19 (rig 



left figur. 



As mentioned above I think there must be some mistake, when 

 Cl. mentions having seen a frustule of this species with the upper 

 valve of the species above named Heteroneis norvegica. Though I 

 have seen no entire frustule of C. lyra, I should think that A. 

 ScHM.'s illustrations to which I have referred, belong together, which 

 also answers very well to the dimensions. I have repeatedly found 

 this upper valve in connection with a loculiferous rim with loculi 

 on 10 \i.. The species consequently is no Disconeis Cl., but belongs 

 to Cocconeis or Pleuroneis. 



The remarkable lower valve occurred sparsely in my material, 

 but corresponded in size and shape precisely to the supposed upper 

 valve. Its structure is puzzlingly similar to that of small forms of 

 Navicula lyra var. atlantica. On one side of the valve between 

 the furrows and the margin, there is, however, an indistinct blank 

 line or furrow, parallel to the main fui-rows, which is absent in 

 the Navicula mentioned. 



Upper valve with transverse and longitudinal co.sta'. the latter 

 a little closer than the former. Between the costæ there is, tliere- 

 fore, a single row of conspicuous areolæ. 



Rare: Stamsund r (both valves); Stene r (ui)per valve only). 



Distrihution: West coa.st of Norwav. 



