128 p. T. CLEVE, SYNOPSIS OP THE NAVIOULOin DIATOMS 



4. 



{ 



j Central area rea<'hiiig nearly to tlie margin 5. 



\ — — — not more than half the breadth of the valve 9. 



r 1 Valve trochiform . N. Layerheimii Cl. 



— elliptical G. 



. . Central area with a single marginal stria 7. 



— — without — — — 8. 



Isolated stria on one side only ." N. asymmetrica Pant. 



— — — both sides N. ulvacea Berkel. 



„ . Strise 20 in 0,oi mm N. obliqua Greg. 



27 — — N. Rotwann Rabh. 



_ . Central area with a stigma N. mutica KtJTZ. 



— without — 10. 



'I 



{ 



j Ends capitate N. Heufleriann Grdn. 



1'^- 1 f 11 



( — not — 11. 



{Length about 0,04 mm. or more N. hacilliformis Grun. 

 — — 0,025 mm i\^ Haradace Pant. 

 — 0.014 to 0,02 mm. or less 12. 



..„ j Ends rostrate 13. 



\ — rounded 15. 



^„ j Valve biconstricted N. nivalis Ehb. 



' \ — elliptical to lanceolate 14. 



( Strice distinct N. Eotschyi Grun. 



\ — very delicate N. depressa Cl. 



^j. I Valve centrally gibbons N. Seminulum Grun. 



\ — not — — N. minima Grun. 



1. N. minima Griw. (1880). — V. linear with broad rounded ends. L. 0,015; B. 0,004,5 

 mra. Central area small, quadrate. Strise 26 in 0,oi mm., more distant in the middle of the valve, 

 radiate throughout. — N. minutissima Grun. Verh. 1860 p. 552 PL IV f. 2. N. minima Grun. in 

 V. H. Syn. p. 107 PI. XIV f. 15, 16. N. Saugerri var. Grun. in V. H. S. f. 16 b. Synedra pusilla 

 KtJTZ. (according to Grun.). 



Fresh water: Belgium (V. H.). 



Var. atomoidcs Grun. (1880). — V. elliptical. L. 0,oos; B. 0,oo4 mm. Strise 27 to 30 in 

 0,01 mm. — N. atomoides Grun. in V. H. Syn. PI. XIV f. 12—14. 

 Fresh water: Belgium (V. H.). 



2. N. Seminulum Grun. (1860). — V. sublinear, gibbous in the middle, with broad, sub- 

 truncate ends. L. 0,015; B. 0,oo4 mm. Central area qiiadrate, not very large. Strise 20 in 0,oi 

 mm., radiate throughout. — N. Snnimdum Grun. Verh. 1860 p. 552 PI. IV f. 3. Lagst. Spitsb. 

 D. PI. II f. 9. V. H. Syn. p. 107 PI. XIV f. 8, 9. N. Saugerri Desmaz in V. H. Syn. f. 8 a'. 



Fresh or slightly brackish water: Spitsbergen (Lagst.), Sweden (Bollnas in Hels^ingland, 

 Koon in Bohuslan)! Belgium (V. H.), Japan! Greenland! 



Var. fragilarioides Grun. (1880). — Strise somewhat coarser. — Grun. in V. H. Syn. f. 10. 



3. N. Itotseana Rabh. (1852). — V. elliptical with rounded ends. L. 0,oi3 to 0,024; B. 0,oo6 

 to 0,008 mm. Central area large and broad, reaching near to the margin. Terminal fissures of 

 the median line in contrary direction. Strise about 28 in 0,oi mm., radiate throughout. — Stauro- 

 neis Rotmma Rabh. Hedw. I p. 103 PI. XIII f. 7 (1852). Grun. Verh. 1860 p. 565 PI. VI f. 14. 

 Stauron. minutissima Lagst. Spetsb. D. p. 39 PI. I f. 13 (1873). Stanron. ovalis Greg. M. J. IV 

 PI. I f. 36 (1856). Stauron. Cohnii Brun D. des Alpes p. 91 PI. IX f 10 (1880). Naric. liotceana 

 V. H. Syn. PI. XIV f. 17^19. 



Fresh water: Spitsbergen (Ldt), Sweden! Finland! Austrian alps (Grun.). 



Var. excentrica Grun. (1880). — Median line somewhat excentric. — Grun. in V. H. Syn. 

 XIV f. 20. 



Var. oblongella Grun. (1880). — Valve narrow elliptical. — Grun. in V. H. S. XIV f. 21. 

 Nav. oblongella Grun. Verh. 1860 p. 551 PI. IV f. 4? 



