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



I Central area reaching nearly to the margin 5. 



\ — — — not more than half the breadth of the valve 9. 



Valve trochiform . . N. Lagerheimii Cl. 



elliptical . . . 6. 



Central area with a single marginal stria . . . . . ... 7. 



without — — — ... . . 8. 



I Isolated stria on one side only . . . N. asymmetrica Pant. 



\ — — — both sides N. ulvacea Berkbl. 



I Strise 30 in 0,oi mm. . . . . . . . N. obliqua Geeg. 



\ — 27 — — N. Rotmana Rabh. 



I Central area with a stigma N. mutiea KtJTZ. 



\ — — without — 10. 



{Ends capitate .... . . . . . . N. ffeufleriana Geun. 

 - not — 11. 



{Length about 0,04 mm. or more . . . . . N. bacilliformis Gbun. 

 — — 0,026 mm. . .... N. Haradaoe Pant. 

 — 0.014 to 0,02 mm. or less ... . . 12. 



{Ends rostrate . . . . ... 13. 

 — rounded ... . . 15. 



I Valve biconstricted . . . . . . N. nivalis Ehb. 



\ — elliptical to lanceolate . 14. 



f Striae distinct ... N. Kotschyi Gbtjn. 



\ — very delicate . . N. depressa Cl. 



I Valvi 



10. 



12. 

 13. 

 14. 



... . Valve centrally gibbons N. Semihulum Geun. 



not — — N. minima Grtjn. 



1. N. minima Grun. (1880). — V. linear with broad rounded ends. L. 0,oi5; B. 0,oo45 

 mm. Central area small, quadrate. Striae 26 in 0,oi mm., more distant in the middle of the valve, 

 radiate throughout. — N. minutissima G-run. Verh. 1860 p. 552 PI. IV f. 2. N. minima Geun. in 

 V. H. Syn. p. 107 PL XIV f. 15, 16. N. Saugerri var. Gbun. in V. H. S. f. 16 b. Synedra pusilla 

 KuTZ. (according to (xrun.). 



Fresh water: Belgium (V. H.). 



Var. atomoides (xRUN. (1880). — V. elliptical. L. 0,oo8; B. 0,oo4 mm. Strise 27 to 30 in 

 0,01 mm. — iV. atomoides Grun. in V. H. Syn. PI. XIV f. 12—14. 

 Fresh water: Belgium (V. H.). 



2. N. Seminulum G-run. (1860). — V. sublinear, gibbous in the middle, with broad, sub- 

 truncate ends. L. 0,oi5; B. 0,oo4 mm. Central area quadrate, not very large. Strise 20 in 0,oi 

 mm., radiate throughout. — N. Seminulum (tRUN. Verh. 1860 p. 552 PI. IV f. 3. Lagst. Spitsb. 

 D. PI. II f. 9. V. H. Syn. p. 107 PL XIV f. 8, 9. N. Saugerri Desmaz in V. H. Syn. f. 8 a'. 



Fresh or slightly brackish water: Spitsbergen (Lagst.), Sweden (Bollnas in Helsingland, 

 Koon in Bohuslan)! Belgium (V. H.), Japan! Greenland! 



Var. fragilarioides Grbn. (1880). — Strise somewhat coarser. — Grun. in V. H. Syn. f. 10. 



3. N. Botseana Rabh. (1852). — V. elliptical with rounded ends. L. 0,oi3 to 0,024; B. 0,oo6 

 to 0,008 mm. Central area large and broad, reaching near to the margin. Terminal fissures of 

 the median line in contrary direction. Strise about 28 in 0,oi mm., radiate throughout. — Stauro- 

 neis Boteeana Rabh. Hedw. I p. 103 PL XIII f. 7 (1852). Grun. Verh. 1860 p. 565 PL VI f. 14. 

 Stauron. minutissima Lagst. Spetsb. D. p. 39 PL I f. 13 (1873). Stauron. ovalis Greg. M. J. IV 

 PL I f. 36 (1856). Stauron. Cohnii Brun D. des Alpes p. 91 PL IX f. 10 (1880). Navic. Boteeana 

 V. H. Syn. PL XIV f. 17—19. 



Fresh water: Spitsbergen (Ldt), Sweden! Finland! Austrian alps (Grun.). 



Var. excentrica Grun. (1880). — Median line somewhat excentric. — Grun. in V. H. Syn. 

 XIV f. 20. 



Var. ohlongella Grun. (1880). — Valve narrow elliptical. — Grun. in V. H. S. XIV f. 21. 

 Nav. ohlongella Grun. Verh. 1860 p. 551 PL IV f. 4? 



