132 P. T. CLEVE, SYNOPSIS OF THE NAVICULOII) DIATOMS. 



Artificial key. 



Larger — L. 0,o.| or more 7. 



^ I Small forms. L. 0,02 mm. or less 2. 



„ , Stri» 13 to 16 in 0,oi mm 3 



much finer 4 



M 



Strise nearly parallel N. Scutiim V. H. 



— radiate — N. infirma Geuii. 



4. 



M 



j Stria) abont SI in 0,0 1 mm N. confervacea KtiTZ. 



\ — — 33 — — ..'.'.... 5. 



, I Valve gibbous in tlie middle and at the ends N. contenta Gbun.. 



' \ — — — — but not at the ends 6. 



Valve sublinear -.-, .,- N. Flotoivii Gbuk. 



subelliptical N. perpusilla Gbun. 



_ I Valve with nndulated margins N. polygibha Pant. 



I — — non — — 8. 



o j Valve elliptical with rounded ends 9. 



\ — lanceolate or fusiibrm 11. 



Q ( Terminal fissnres in contrary direction N. fallax Cl. 



'I — — — the same — 10. 



, ) Puncta twice as close as the strise N. Beta Cl. 



' \ — as close as the strise ' . N. Hochstetteri Getjn. 



.... J Valve broadly lanceolate 12. 



f Ar. 

 1(3. 



I — narrow — or fusiform 16. 



i Puncta forming straight, longitudinal rows N. lota 



I - — undulating — — 13. 



ea broad 14. 



narrow 15. 



Striae 10 in 0,01 mm , iV^. semitecta A. S. 



— 13 — N. occidentalis Cl. 



— ly — N. definita Geove a. Stuet. 



Valve rostrate N. mocsnrensis Pant. 



15. •[ " obtnse y. Bäumleri Pant. 



acQte J\^. Kappa Cl. 



Valve fusiform 17. 



— narrow lanceolate N. Foliola Bedn a. Temp. 



..„ , Strise radiate in the ends N. monmonthiana Gbun. 



i Strise radiate 

 — almost parallel 18. 



..„ j StricE »crossed by two lines» N. fusoides Gbun. 



\ — not N. inornata Gbun. 



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

 L. 0,007 to 0,0 i; B. 0, 002 to OtOoa.») mm. Axial area narrow, linear, slightly dilated in the middle. 

 Strise almost parallel 36 in 0,oi mm. — N. trinodis V. H. Syn. Pl. XIV f. 31 a. iN". contenta 

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



Fresh water (on moist rocks and mosses): Sweden (Trollhättan)! Finland (Åbo)! Belgium 

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



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

 ding to Grun.). Nav. trinodis var. hiceps 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. Strife radiate, 35 in O.oi mm. — Grun. 

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



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



