KONGL. SV. VET. AKADEMIENS HANDLINGAE. BAND. 27. N:0 3, 39 



^ , J Length about 0,1 mm 15. 



' \ — — 0,06 mm 16. 



^, ( Striae 8 in 0,oi mm J\^. latissima Gbeg. 



"1—17 — - N. My Ch. 



^„ / Central area bordered with a circlet of elongated pnncta N. Zeta Cl. 



■ \ — — not — — — — — 17. 



..„ I Central area large N. Febigerii Cl. 



1 — — small N. Neumayeri Pant. 



[ Valve biconstricted N. JSfovce Gwinceensis Temp. 



18. •! — constrieted in the middle 19. 



I — not constrieted 21. 



.,(, J Pnncta large, irregular N. bilobata Leud. Foetm. 



{ 



arranged in transverse rows 20, 



1 Transi 



81. 



g„ 1 Transverse rows of pnncta 6 in 0,0 1 mm N. ceylanensis Leud. Foktm. 



— 12 — — N. sublyrata Gbun. 



I Valve rostrate 22. 



not — 31. 



I Central area large 23. 



\ — — small or indistinct 25. 



g„ j Puncta closer than the strise N. amphibola Cl. (JV. Galikii Pant.). 



( — and striae eqnidistant 24. 



f Pnncta forming straigbt longitudinal rows N. Gamma Cl. var. 



24. •! — — curved — - — S'. baccata Brun. a. Temp. 



[ — — undnlating — — N. maculata Bail. 



„. ( L. 0,03 mm 26. 



L. 0,04 to 0,1 mm. or more 27. 



Striae 10 in 0,oi mm N. Omicron Cl. 



17 — — N. Omega Cl. 



„ . Ends apiculate N. diffusa A. S. (N. conspersa Pant.) 



^'- ^ not - 28. 



{ 



26. 1^*^' 



) Ene 



I Terminal iissnres large, hook-shaped N. arabica Grun 



Terminal fissnres in contrary directions N. Epsilon Cl. 



^^- ' — — small 29, 



29. •! 



\ — — — the same — 30. 



g_ I Puncta eqnidistant i\^. monilifera Cl. 



1 — more crowded at the margin and the median line N. transfuga Grun. 



g.( J Valve elliptical 32. 



\ — lanceolate 39. 



Pnncta irregnlar N. margaritifera Truan. a. Witt. 



— in transverse rows 33. 



Puncta closer than the striEe N. Jentzschii Grun. 



— eqnidistant with the striae, or wider 34. 



32. I 



33. I 



Q, j Length 0,02 to 0,04 mm 35 



\ — 0,06 to 0,1 mm 36. 



J Pnncta near the median line in longitndinal straight rows N. fraudulenta A. S. 



\ — not forming straight rows N. torneensis Cl. 



I Puncta wider than the striae N. sparsipunctata Grove a. Stukt. 



38. {' 



^^- \ - not - - 37. 



„_ f Puncta in slightly cnrved longitndinal rows N. Schulzii Kain. 



' \ — — nndulating — — 38. 



Central area transverse N. oscitans A. S. 



rounded N. glacialis Cl. 



„_ I Preshwater habitat 40. 



\Marine — 42. 



^^ I Central area small 41. 



■ \ — — large N. Gamma Cl. 



. I j Pnncta in straight longitudinal rows N. Toidce Pant. 



■ \ — — nndulating — — N. lacustris Greo. 



. ) Axial area narrowed towards the middle and the ends N. gramdata Bail. 



{ 



not — — — — — -43. 



