144 P. T. rLKVF,, SYNOPRIS OF TIIE NAVICUI.OID DIATOMS. 



^„ I Valve biconstrifteil 19. 



•^*'- 1 - not - 20. 



J Small (L. 0,03 to 0,04 iiim.) .S'. Legnmen Ehb. 



I Large (L. 0.2 mm.) S. Fuhiien Btw. 



( Valve fusiform .S'. Frfinenfddtidnii Gri-k. 



20. ■{ — rhombic-lanccolatft .V. nrntn W. Sm. 



I — lanceolate or linear-lanceolate 21. 



^^ I Large (L. 0,i2 to 0.2 nira.) .S'. jaranica Grun. 



■' ■ i Small (L. less tlian 0,i)7 mm.) 22. 



jj„ J Strise aliout 15 in 0,01 mm .S'. ohlnnga Gkux. 



■""■ \ — fine 33 — 23. 



g., J Entls rostrate S. parvula Grun. 



I — non-rostrate .S'. obtusa Lägst. 



„ , J Branclies of tlie stauros parallel -S. Sagitta Cl. 



"^ ■ \ — — ilivergent 25. 



j Freshwater liabitat 26. 



""'' I Marine 27. 



j Ends rostrate S. Crucinda Gruk. 



1 — non-rostrate 8. andicoln Cl. 



,.,„ I Valve lanceolate, subrostrate S. Reichnrdtiana Grun. 



■^ ■ \ — broadly elliptical 28. 



I Stauros witli verj' divergent branches S. Lindigiana Grun. 



■^ ■ I — — less — — S. ovata Grun. 



I Median line sigmoid or with tlie terminal tissures in contrary directions 30. 



"■■ I — — not sigmoid the same — or indistinct 31. 



J Median line sigmoid lY. tiimida Bréb. 



' \ — — straigbt X. aiiklandica Grun. 



J Ends with diapliragms N. hielegans Grove & Sturt. 



' ■ \ — without — 32. 



,„ I Median line flexuose N. plicatula Grun. 



1 — — straiglit 33. 



,,„ I Frustule arcuate N. Garkeana Grun. 



\ — not 34. 



, Striffi verv fine (28 to 30 in 0,0 1 mm.) 35, 



-{ 



I Strife verv 



\ — 15 to 20 in 0,01 mm 37. 



Zone broad IC. Hyalosira Cl. 



— narrow 36. 



)Ends acute X ap07iina KuTZ. 



'I — rostrate-capitate N. Bnlnheimii Grun. 



Valve linear, obtuse N. Scopnlorum Breb. 



— — lanceolate 38. 



— rhombic — 39. 



— elliptic — aV. suaris Cl. & Grove. 



— rostrate JV. .limhoi Pant. 



.„ I Zone broad N. complanata Grun. 



\ — narrow -V. plicata Donk. 



„^ I Frnstules in gelatinous tiibes X. Grcfillei Ag. 



"*"• \ - free 40. 



J Obtnse K. Weissfngii Grun. 



\ Acute or subacute 41. 



... J Median line reacliing to the ends N. Libellns Greo. 



■^- t - - not - - 42. 



J Terminal fissnres indistinct iV. rhombicn Greg. 



"'I — — book-shaped JV. hamiilifera Grun. 



1. S.? pellucida Cl. (1<S83). — V. elliptical, witli broad, rounded ends. tliiii and coiivex. 

 L. 0,053 to O, Of,; B. O,oit; to 0, 023 min. Median line with tlie terminal tissnre.'* indistinct because 

 the convexity of the valve. Central nodnle transversely dilated to a short .'stauros. Axial area 

 indistinct; central small. Strise 16 to 21 in 0,oi mm. obscure, punctate. 



