128 v. T. CLEVE, SYNOPSIS OF THK NAVICDLOID DIATOMS. 



Central area reacliiiig nearly to the margin 5 



I' 



not more than half the breadth of the valve 9. 



^ Valve trochiforni X. Lagerheimii Cl. 



— elliptical 6. 



,. J Central area with a singie marginal stria 7. 



\ — — without — — — 8. 



Isolated stria on one side only N. asymmetrica Pant. 



I Isolated stria 



^ both sides , . N. ulvacea Bebkel. 



Striae 20 in 0,oi mm N. obliqua Geeg. 



27 — — N. Rotceana Eabh. 



j Central area with a stigma N. nnitica KuTZ. 



\ — — without — 10. 



.,„ 1 Ends capitate N. Heufieriana Gbun. 



not — 11. 



{ 



{' 



f Length abont 0,04 mm. or more JV^. bacilli/ormis Grun. 



11. < — — 0,025 mm N. Haradace Pant. 



I — 0.014 to 0,02 mm. or less 12. 



..q ( Ends rostrate 13. 



^' \ — rounded 15. 



.. (Valve biconstricted N. nivalis Ehb. 



15. {^^^ 



elliptical to laneeolate 14. 



distinct N. Kotschyi Gbun. 



very delicate K. depressa Cl. 



centrally gibbous N. Seminulum Gbun. 



not — — K. minima Gbun. 



1. N. minima Grun. (1880). — V. linear with broad rounded ends. L. 0,oi5; B. 0,oo4 5 

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

 radiate throughont. — N. minuHssima Grun. Verh. 1860 p. 552 Pl. TV f. 2. i\^. minima Grun. in 

 V. H. Syn. p. 107 Pl. XIV f. 15, 16. N. Saugerri var. Grun. in V. H. S. f. 16 b. Syuedra pusiUa 

 KtJTZ. (according to Grnn.). 



Fresh water: Belgiiim (V. H.). 



Var. atomoides Grun. (1880). — V. elliptical. L. 0,oo8; B. 0, 004 mm. Striae 27 to 30 in 

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

 Fresh water: Belginm (V. H.). 



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

 truncate ends. L. 0,015; B. 0, 004 mm. Central area quadrate, not very large. Strise 20 in 0, 01 

 mm., radiate throughont. — N. Seminulum Grun. Verh. 1860 p. 552 Pl. IV f. 3. Lägst. Spitsb. 

 D. Pl. 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 (Lägst.), Sweden (Bollnäs in Helsingland, 

 Koön in Bohuslän)! Belginm (V. H.), Japan! Greenland! 



Var. fragilarioides Grun. (1880). — Striee somewhat coarser. — Gi'un. in V. H. Syn. f. 10. 



3. N. Rotaeana Rabh. (1852). — V. elliptical with rounded ends. L. O.ois to 0,024; B. O.ooe 

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

 the median line in contrary direction. Striee about 28 in 0, 01 mm., radiate throughont. — Stauro- 

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

 Stauron. minutissima Lägst. Spetsb. D. p. 39 Pl. I f. 13 (1873). Sfauron. oralis Greg. M. J. IV 

 Pl. I f. 36 (1856). Stauron. Cohnii Brun D. des Alpes p. 91 Pl. IX f. 10 (1880). Xaric. Rotceana 

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

 Nav. oblongella Grun. Verb. 1860 p. 551 Pl. IV f. 4? 



