14. 

 15. 

 1(5. 

 17. 



KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 27. N:0 3, 89 



{ 



Length about 0,1 mm 15. 



— — O,0fi mm lU. 



J Striae 8 in 0,0 1 mm X. latissima Greg. 



1—17 — — N. My Ci.. 



1 Central area bordered with a circlet of elongated puncta A^. Zeta Cl. 



\ — — not - — — — - 17. 



( Central area large N. Febigerii Cl. 



I — — small X. Neumayeri Pant. 



j Valve biconstricted N. Novce Guinwensis Temp. 



18. •! — constricted in the middle 19. 



I — not constricted 21. 



J Puncta large, irregular N. bilobata Leud. Foktm. 



\ — arranged in transverse rows 20. 



j Transverse rows of puncta 6 in 0,0 1 mm N. ceylanensis Leud. Fohtm. 



I — — --12 — — N. sublyrata Grun. 



j Valve rostrate 22. 



\ — not — 31. 



J Central area large 23. 



I — — small or indistinct 25. 



i Puncta closer than the striae N. amphibola Cl. (N. Galikii Pant.). 



I — and striae equidistant 24. 



{ Puncta foiming straight longitudinal rows N. Gamma Cl. var. 



24. ■! — — curved — — N. baccata Brun. a. Temp. 



( — — undulating — — N. maculata Bail. 



j L. 0,03 mm 26. 



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



j Stris 10 in 0,oi mm N. Omicron Cl. 



\ — 17 — -- N. Omega Cl. 



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



\ — not — 28. 



„ J Terminal fissures large, hook-shaped N. arabica Grdn. 



19 



20 

 21 



22. 

 23. 



( Termii 



{ " 



30. { 



{ 

 \ 



83. I ^^ 



— small 29. 



„j . Terminal fissures in contrary directions N- Epsilon Cl. 



— — — the same — 30. 



Puncta equidistant N. monilifera Cl. 



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



„.. 1 Valve elliptical 32. 



lanceolate 39. 



„g . Puncta irregular N. margaritifera Tbtjan. a. Witt. 



in transverse rows 33. 



Puncta closer than the striae N. Jentzschii Grun. 



equidistant with the stria, or wider 34. 



Length 0,0 2 to 0,04 mm 35. 



34. 

 35. 

 36. 

 37. 

 38. 

 39. 

 40. 

 41. 

 42. 



j Len 



( Puncta near the median line in longitudinal straight rows N. fraudulenta A. S. 



\ — not forming straight rows N. torneensis Cl. 



j Puncta wider than the striae N. sparsipunctata Grove a. Sturt. 



\ — not — — 37. 



( Puncta in slightly curved longitudinal rows N. Schulzii Kain. 



\ — — undulating — — 38. 



I Freshwater habitat 40. 



\ Marine — 42. 



j Central area small 41. 



) — — large N. Gamma Cl. 



J Puncta in straight longitudinal rows N. Toiilce Pant. 



I — — undulating — — N. lacustris Greg. 



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



\ — — not — — — — — -43. 



Central area transverse N. oscitans A. S. 



— rounded N. glacialis Cl. 



