132 p. T. CLEVE, SYNOPSIS OF THE NAVICULOIO DIATOMS. 



Artificial key. 

 ^ j Small forms. L. 0,o2 mm. or less 



{' 



{' 



\ Larger — L. 0,04 or more .... 7. 



Striae 13 to 16 in 0,oi mm 3. 



much finer 4. 



( Striae nearly parallel N. Scutum V. H. 



\ — radiate — . . N. infirma Gruii. 



Stria about 21 in 0,01 mm N. confervacea KtJTZ. 



— 33 — — 5. 



f Valve gibbous in the middle and at the ends .....' N. contenta Grun.. 



\ — — — — but not at the ends . . ... 6. 



Valve sublinear N. Flotowii Gkun. 



subelliptical N. perpusilla Grun. 



I Valve with undulated margins N. polygihba Paht. 



I — — non — — . , 8. 



Valve elliptical with rounded ends 9- 



lanceolate or fusiform . ■ . . 11. 



{Terminal fissures in contrary direction . . . . .... . ■ . N. fallax Cl. 



'— — — the same — . . ... . ... 10. 



{Puncta twice as close as the striae . ... . . . N. Beta Cl. 



— as close as the striae . . . . ... N. Hochstetteri Grun. 



.( ^ I Valve broadly lanceolate . . ..... . .12. 



\ — narrow — or fusiform . . . . . .... 16. 



..„ i Puncta forming straight, longitudinal rows . N. Iota Cl. 



■ \ — — undulating — — . . ... 13. 



^„ ( Area broad ..... . 14. 



\ • — narrow .... . . 15. 



[ Striae 10 in 0,01 mm. . . . . N. semitecta A. S. 



14. < — 13 — . . . . . N. occidentalis Cl. 



I — 19 — . . . . JV. definita Grove a. Stubt. 



I Valve rostrate N. mocsarensis Pant. 



15. ■! — obtuse ... . N. Bdumleri Pant. 



I — acute N. Kappa Cl. 



.,„ j Valve fusiform 17. 



\ — narrow lanceolate ... . N. Foliola Bbun a. Temp. 



9. 

 10. 



..„ j Stria 



Striae radiate in the ends . N. monmouthiana Grun. 



8 I' 



\ — not N. inornata Grun. 



almost parallel . ... 18. 



,_ , Striae ^crossed by two lines» . N. fusoides Grun. 



1. N. contenta Grun. (1880). — V. linear, gibbous in the middle, with broad capitate ends. 

 L. 0,007 to 0,01 ; B. 0,oo2 to 0,oo25 mm. Axial area narrow, linear, slightly dilated in the middle. 

 Striee almost parallel 36 in 0,oi mm. — N. trinodis V. H. Syn. PL XIV f. 31 a. N. contenta 

 Grun. in V. H. Syn. p. 109. 



Fresh water (on moist rocks and mosses): Sweden (TroUhattan)! Finland (Abo)! Belgium 

 (V. H.), Salzburg! Amsterdam Island! 



Var. biceps Arnott Ms. — V. not gibbous in the middle. — Diadesmis biceps Arnott (accoi^- 

 ding to Grun.). Nav. trinodis var. biceps V. H. Syn. XIV f. 31 b. 



Fresh water: Belgium (V. H.), Ecuador! 



2. N. (Diadesmis) Flotowii Grun. (1880). — V. narrow, lanceolate, with broad, obtuse 

 ends. L. 0,oi5; B. 0,oo4 mm. Area narrow, lanceolate. Strise radiate, 35 in 0,oi mm. — Grun. 

 V. H. Syn. p. 109 PI. XIV f. 41. 



Fresh water: Belgium (V. H.), France (V. H. T.). 



