78 



r. T. CLEVE, SYN()r,Sl!S OF THE NAV1CL'L(>11> DIATOMS. 



1«. 



17. 

 IH. 

 Kt. 

 W. 



n. 



22. 

 23. 



24. 



25. 



26. 

 27. 

 28. 

 20. 

 :!(). 

 31. 

 32. 

 33. 

 34. 

 35. 



3t;. 



37. 

 38. 

 39. 

 40. 

 41. 

 42, 

 43. 

 II. 



) Costse iiurassate at the margin 1>. Afloiiis Briin. 



\ — not — — 17. 



( Segments almost orbicular JJ. intcrrupta KiJTZ. 



I — elongate-elliptical D. Guinardiana Brun. 



Valve not constricted 19. 



— liandnriforni ^ 23. 



Valve very convex and thick D. circumnodosa Brun. 



— not — — 20. 



Valve elliptical D. C'yuihin A. S. 



— linear 21. 



Furrows decreasing in breadth from the middle D. mnnda Jan. 



— of equal breadth throughout 22. 



Central nodule small L). mcditi'rrtinea Grun. 



— — large D. rontiytta A. S. 



J Furrow crossed by cost;e D. Lctounicnrnii Ct,. 



I — without or with rudimentary costa> 24. 



j ('ost* 4 to 7 in 0,01 mm /). niusca'formis Grun. 



j — 7 to 8 — D. covstrirtn Grun. 



I — 11 to 12 — D. incur nata Greg. 



j Costa crossed by a single longitudinal rib 26. 



\ — — several - ribs 35. 



I — alternating with double rows of alveoli 61. 



I Valve not constricted 27. 



\ — constricted 29. 



L. 0,02 to 0,03 mm 28. 



L. 0,04 to 0,08 mm D. lincata Donk. 



Furrows broad . . . ' D. discreprivs A. S. 



— narrow D. Papula A. S. 



Valve gently constricted 30. 



— deeply — 34. 



Furrows decreasing in lireadth IVnm the middle 1>. Viiula A. S. 



— of almost e(iual breadth 31. 



Furrows very broad I), hinaria A. S. 



— not' — 32. 



Longitudinal rib in the middle of the striic 33. 



— — marginal D. snhchicta A. S. 



Rib narrow D. exemta A. S. 



— broad D. dcmta A. S. 



L. about 0,03 mm D. bomhiformis Cl. 



L. 0,07 to 0,1 mm D. rortrctata A. S. 



Valve constricted 36. 



— not - 50. 



Valve with ocelli D. areolata Cl. 



without 37. 



Valve strongly constricted 38. 



— slightly — 45. 



j Segments orbicular I). Clepsydra, Cl. 



I — elli|itical or deltoid 39. 



j Costae alternating with faint alveoli D. Prmstcs A. S. 



\ — — — distinct — 40. 



) Ribs forming undulating rows D. splrndida Grko. 



\ — — straight or curved 41. 



I L. 0,0 1 or less D. Griiiidleri A. S. 



( L. large. 



42. 



J Furrows indistinct i>. Weinsjloyii A. 8. 



( — distinct 43. 



j Ribs two to live on each side of the median line 44. 



I — eight to ten D. Kiltzingii Grun. 



I Transverse cost* 5 to M in O.ni mm D. Bombus Ehb. 



1 — — 8 to 1.3 — D. clirrsovensis Grun. 



