Diatoms. 



207 



H. AUuianniana (Greg.). 



Pinnularia A. Greg. Diat. of Clyde p. 488, pi. IX, f. 21. Cocconeis quarnerensis 



A. Schm. Novels. Diat. pi. Ill, f. 16; Atlas pi. 192, figs. 20—24. Rhaphoneis 



n. Grot. Wien Verb. 1862, p. 381, pi. 7, f. 24. Navicula orulum A. Scum. 



Nords. Diat. pi. II, f. 12. Hetercneis q, Cl. 1. e. p. 184. 



„ Costa? apparently marginal, strong, about 20 in 0.001", giving 

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

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

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

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

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

 are so strong and conspicuous there.'" Greg. 1. c. 



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

 Pinnularia Allmanniana Greg, is synonymous to Cocconeis quar- 

 nerensis GrRUN. Size, shape and structure agree very well in both 

 species. 



There seems to be a marginal rim which has. however, only 

 faint traces of loculi. 



Hare: Stamsund r. Stene r. 



Distribution: Coasts of the North Sea. Arctic regions. The 

 Mediterranean. 



H. norve&ca (Grot.?) 



Cocconeis norvegica Grot., Cl. M0ll. Diat. no. 102 (upper valve, teste Cl.) 

 A. Schm. Nords. Diat. pi. Ill ,f. 18, 1 (upper figure. „Cocconeis sp", upper valve). 



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 striae, in the median part of the valve coarser and 

 more conspicuous, about 15 on 10 |jl, 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 lie has 

 found a frustule of ( 'occoneis lyra with an upper valve like that 

 illustrated by A. Schm. 1. c. (pi. III. 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'ooconois Ehrb., Cl. 



Valves ecostate, with a marginal loculiferous rim, dissimilar in 

 structure. 



C. scutellum Ehrb. 

 Ehrb. Infus. p. 194, pi. 14. f. 8. Van Hedrck Synops. p. 132. [.1. 29, figs. 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 unfrequent, in different forms which only badly answer 



to the varieties described: Stamsund r. Svolvser {-, 0stnesfiord r. 

 Stene r. 



Distribution : Cosmopolitan. 



C. dlstans Gbbg., a. Schm. 



Greg. Diat. of Clyde, p. 490. pi. IX, f. 23 (ls.">7. non Micr. Journ. Ill, p. 39. 



pi. IV. f. 9. 1855 which Greg. I. c. p. 491 himself declares to be a var. of '. 



scutellum illustrated as ('. distans by mistake). A. Schm. Nords. Diat. pi. III. 



figs. 22 2:: (forma minima Perag.). 



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

 1. c. (f. 23 entire frustule) occurred. They had no loculiferous 

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

 distinct stria?. 



There is. however, such a remarkable agreement with a form 

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

 first was figured by Gregory 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 ('. scutellum just mentioued differs remarkably 

 from the common forms. There is a narrow 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. Strke 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 striae somewhat closer and less conspicuous than the 

 marginal stria.' of the valve. 1.5 — 16 one 10 ;jl. 38 \i x 29 |i. 



Smaller specimens seem to pass insensibly into such forms. 

 which A. Schm. has figured 1. c. 



Very rare: Stamsund r. 



Distribution: Coasts of the North Sea. The Mediterranean. 

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



C. lyra A. Schm. 

 A. S( iim. Nords. Diat. pi. in, f. 19 (right figure lower valve, left figure upper 



valve). 



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 6 loculi 

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

 to ( 'occont is up Pleurom is. 



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 furrows, which is absent in 

 the Navicula mentioned. 



Upper valve with transverse and longitudinal eostse, the latter 

 a little closer than the former. Between the eostse there is. there- 

 fore, a sinule row of conspicuous areola*. 



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



Distribution: West coast of Norway. 



