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



Artificial key. 



Small forms. L. 0,o2 mm. or less 2. 



Larger — L. 0,oj or more 7. 



Striae 13 to 16 in 0,oi mm 3. 



much liner 4. 



I Strise nearly parallel N. Scutum V. H. 



\ — radiate — N. infirma Gruii. 



Stria) about 21 in 0,oi mm N. confervacea KtJTZ. 



— 33 — — 5. 



Valve gibbous in the middle and at the ends N. confenta Grun.. 



— — — but not at the ends 6. 



Valve sublinear N. Flotowii Grun. 



subelliptical N. perpusilla Grun. 



Valve with undulated margins N. polygihha Pant. 



— non — — 8. 



Valve elliptical with rounded ends 9. 



lanceolate or fusiform 11. 



Terminal fissures in contrary direction N. fallax Cl. 



— — the same — 10. 



j Puncta twice as close as the strise iV. Beta Cl. 



I — as close as the strise iV. Hochstetteri Grun. 



j Valve broadly lanceolate 12. 



I — narrow — or fusiform 16. 



j Puncta forming straight, longitudinal rows N. Iota Cl. 



( - — undulating — — 13. 



( Area broad • 14. 



\ — narrow 15. 



i Strise 10 in 0,oi mm N. semitecta A. S. 



14. < — 13 — N. occidentalis Cl. 



I ^ 19 — N. definita Grove a. Sturt. 



I Valve rostrate N. mocsarensis Pant. 



15. •! — obtuse N. Bdumleri Pant. 



I — acute N. Kappa Cl. 



j Valve fusiform 17. 



( — narrow lanceolate N. Foliola Beun a. Temp. 



I Striae radiate in the ends N. monmouthiana Grun. 



I — almost parallel 18. 



Striifi i>crossed by two liness N. fusoides Grun. 



not N. inornata Grun. 



16. 

 17. 



18. 



{ 



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

 L. 0,007 to 0,0 I ; B. 0,002 to 0,()(i2.'-) mm. Axial area narrow, linear, slightly dilated in the middle. 

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

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



Fresh water (on moist rocks and mosses): Sweden (Trollhattan)! Finland (Abo)! Belginm 

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



Var. hiccps Arnott Ms. — V. not gibbous in the middle. — Diadesmis biceps Arnott (accor- 

 ding to Grun.). Nav. trinodis v(ir. biceps V. H. Syn. XIV f. ol b. 



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



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

 ends. L. 0,oi.'j; B. 0,oo4 mm. Area narrow, lanceolate. Striae radiate, 35 in 0,oi mm. — Grun. 

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



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



