144 P. T. PLEVE, SYNOPSIS OF THE NAVIPULOID DIATOMS. 



^„ ) Valve biconstricted 19. 



I — not — 20. 



I Small (L. 0,03 to 0,04 mm ) .S', Legnmen Ehb. 



\ Large (L. 0,2 mm.) 5'. Fuhnen Btw. 



( Valve fusiform .S'. Franenfeldtiana Grun. 



20. < — rhombic-lanceolate S. acuta AV. Sm. 



I — lanceolate or linear-lanceolate '. 91. 



jj ) Large (L. 0,i2 to 0.2 mm.) S. javnnica Grun. 



I Small (,L. less than 0,u7 mm.) 22. 



jjjj J Striae about If) in 0,ni mm ,S'. ohlovga Grun. 



-'■ t — fine 23 — 23. 



jj j Ends rostrate S. parvula Grun. 



*" I — non-rostrate S. ohtnsa Lagst. 



^. j Brandies of the stauros parallel ;S. Sagitta Cl. 



" ■ \ — — divergent 25. 



jj. j Freshwater habitat 26. 



( Marine 27. 



J Ends rostrate S. Crucicula Grun. 



'1 — non-rostrate S. nndicola Cl. 



^„ j Valve lanceolate, subrostrate S. ReicJiardfiana Grun. 



"'■ \ — broadly elliptical 28. 



Stauros with verj' divergent branches ,S. Lindigiann Grun. 



„^ j Stauros wit 

 2«- I _ _ 



less — — ;S. orata Grun. 



) Median line sigmoid or with the terminal fissures in contrary directions 30. 



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



Median line sigmoid N. tumida Br:6b. 



straight .V. anklandica Grun. 



J Ends with diaphragms N. inelegans Grove & Sturt. 



' • 1 — without — ■ 32. 



.jj) ( Median line flexuose N. i)li(atnla Grun. 



"^ — — straight 33. 



Frustule arcuate N. Garheana Grun. 



30. I 



{ 



-[ 



^^- ' not 34. 



„. I Striae very fine (2(S to 30 in 0,oi mm.) 35. 



\ — 15 to 2t) in 0,01 mm 37. 



Zone broad N. Hyalosira Ol. 



narrow 36. 



„,. I Ends acute iV. apoinna Kvtz. 



I — rostrate-capitate A. Bvlnheimii Grun. 



Valve linear, obtuse K. Sropvlorurii Breh. 



— — lanceolate 38. 



— rhombic — 39. 



— elliptic — X. suavis Cl. & Grove. 



— rostrate N. Jiniboi Pant. 



„^ , Zone broad N. complanafa Grun. 



— narrow X. plicata Donk. 



„^ j Frustules in gelatinous tuiies X. Grevillei Ac;. 



' • \ — free 40. 



. j Obtuse X. Weissflogii Grun. 



\ Acute or subacute 41. 



... j Median line reaching to the ends X. Lihelltis Greg. 



\ — — not — — 42. 



Terminal fissures indistinct i\^. rhombica Greg. 



— hook-shaped X. haninlifera Grun. 



., I Termiiu'i 

 42. \ _ 



1. S.? pellucidii Cl. (1883). — V. elliptical, with broad, rounded end.s, thin and convex. 

 L. 0,05.3 to 0,()g; B. 0,016 to 0,()2;? mm. Median line with the terminal fis.snres indistinct because 

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

 indistinct; central small. Striic 1() to 21 in 0,oi mm. obscure, punctate. 



