KONGL. SV, VET. AKADBMI!eNS HANDLINGAR. BAND. 27. N:0 3, 39 



^ . J Length about 0,,i mm 15. 



' \ — — 0,06 mm 16. 



..p. ( Striae 8 in 0,oi mm N. latissima Gkeg. 



\ — 17 — — N. My Ch. 



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



16- I _ _ „„t - - - - - 17. 



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



' \ — — small N. Neumayeri Pant. 



j Valve biconstricted . . . . N. Novce GuiwBensis Temp. 



18. < — constricted in the middle 19. 



( — not constricted 21. 



..„ I Pnncta large, irregular .... . N. bilobata Lecd. Fortm. 



\ — arranged in transverse rows ... 20. 



a„ I Transverse rows of pnncta 6 in 0,oi mm N. ceylanensis Leud. Fortm. 



' \ — — — 12 — — N. sublyrata Geun. 



„., 1 Valve rostrate 22. 



^1- \ _ not - . 31. 



„„ i Central area large .23. 



' \ — — small or indistinct ... . .25. 



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



\ — and striae eqnidistant .... . ... 24. 



{Pnncta forming straight longitudinal rows N. Gamma Cl. var. 

 — — curved — — . . . . . . N. baccata Brun. a. Temp. 

 — — undulating — — .... N. maculata Bail. 



„, I L. 0,03 mm 26. 



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



( Stria 10 in 0,oi mm N. Omicron Cl. 



^- \ — n — — N. Omega Cl. 



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



37- I _ n„t - 28. 



„ j Terminal iissures large, hook-shaped . . ' N. arabica Grun. 



■ \ — — small ... . ... 29. 



( Terminal fissures in contrary directions . ... . iV^. Epsilon Cl. 



■ \ — — — the same — 30. 



I Pnncta equidistant N. monilifera Cl. 



I — more crowded at the margin and the median line N. transfuga Grtjn. 



„., j Valve elliptical 32. 



\ — lanceolate ■ 39. 



) Pnncta irregular JV. margaritifera Thuan. a. "Witt. 



' ( — in transverse rows 33. 



( Pnncta closer than the striae . ... N. Jentzschii Grttn. 



■ I — equidistant with the striae, or wider . 34. 



Q. ( Length 0,02 to 0,04 mm . . ... 35. 



I — 0,06 to 0,1 mm 36. 



I Pnncta near the median line in longitudinal straight rows .... N. fraudulenta A. S. 



^^- I _ not forming straight rows N. torneensis Cl. 



f Puncta wider than the striae N. sparsipunctata Grove a. Sttiet. 



\ — not — — 37. 



f Pnncta in slightly curved longitudinal rows N. Schulzii Kain. 



\ — — undulating — — . . 38. 



36. 

 37, 

 38 



J Central area transverse N. oscitans A. S. 



I _ — rounded N. glacialis Cl. 



j Freshwater habitat 40. 



\ Marine — ^2. 



.„ f Central area small ^l- 



■*"•■( large -^. Gamma Cl. 



j Puncta in straight longitudinal rows . N. Toulce Pant. 



*^- I _ — undulating — — N. lacustris Greg. 



f Axial area narrowed towards the middle and the ends N. granulata Bail. 



42- __ not - - - - - 43. 



