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



Nar. bitnminosa is a variable species, which is closely akin to Finnularia, section divergentes. 

 On the other hand some of its varieties seem to be akin to varieties of Nav. Yarrensis. The areas 

 are subject to great variation, and there are gradual passages from forms vs^ith a perfect trans- 

 verse fascia, to forms with the central and axial areas uniting in a lanceolate space. As the 

 most extreme form of this kind I regard Nav. cincta Pant,, vsrhich I know only by the figure in 

 Pantocsek's work. Pantocsbk considers it as a distinct species, and if so another name is neces- 

 sary, as the name cincta has been used for another, well known species. 



2. N. Chyzereii Pant. (1889). — V. elliptic-lanceolate, with obtuse extremities. L. 0,u6b; 

 B. 0,0 19 mm. Axial area distinct, linear, abruptly dilated to an orbicular central area. StricE 8 

 to 10 in 0,0 1 mm. divergent in the middle, convergent at the ends. — Pant. II p. 43 PI. Y f. 96. 



Brackish water: Hungary, fossil! 



3. N. discernenda Pant. (1889). — V. linear-elliptical, with subcuneate ends. L. 0,o3 7 to 

 0,05; B. 0,012 to 0,0 13 mm. Axial area very narrow; central area large, orbicular. Strise 12 to 

 14 in 0,01 mm. divergent in the middle, convergent at the ends. — Pant. II p. 45 PL XXII f. 335. 



Brackish water: Hungary, fossil! 



N. discernenda is closely akin to N. Ghygereii and scarcely more than a small variety with 

 somewhat closer strise. 



4. N. grata Pant. (1889). — V. narrow, elliptic-lanceolate. L. 0,o84; B. 0,oi5 mm. Median 

 pores distant. Axial area narrow linear, strongly dilated in the middle. Strise 11 in 0,oi mm., 

 divergent in the middle, convergent at the ends, their terminations angularly bent. — Pant. II 

 p. 46 PL II f. 21. 



Brackish water: Hungary, fossil (Pant.). 



5. N. elegans W. Sm. (1853). — V. lanceolate, with acute ends. L. 0,i; B. 0,027 mm. 

 Median line with distant central pores and semicircular terminal fissures. Axial area very narrow; 

 central area large, orbicular. Strise 9 in 0,oi mm., strongly divergent in the middle, convergent 

 at the ends. — Br. D. I p. 49 PL XVI f. 137. Donk. Br. D. p. 23 PL IV f. 1. 



Marine to brackish: England! Bohuslan! 



Var. ciispidata Cl. — V. rostrate. L. 0,o8; B. 0,02 mm. Strise closer, about 12 in 0,oi mm. 

 Brackish water: Atlantic coast of North America! 



6. N. lauta Grun. (1888). — V. linear-elliptical, with subcuneate ends. L. 0,095; B. 0,028 

 mm. Axial area lanceolate, dilated in the middle. Median line with the terminal fissures in 

 contrary directions (Grrun.). Strise 13 (9 to 10 Grrun.) in 0,oi mm. 'divergent in the middle, con- 

 vergent at the ends, in the middle alternately longer and shorter. — V. H. Types 542 Bot. 

 Centralbl. XXIII p. 324. Icon. n. Part. I PL I f. 30. 



Brackish water: South Yarra, Australia! 



7. N. megastauros Cl. (1883). — V. elliptic-lanceolate, with subacute ends. L. 0,02; 

 B. 0,008 mm. Axial area indistinct; central large, transverse, dilated to a stauros, reaching nearly 

 to the margin. Strise 16 in 0,oi mm., strongly divergent in the middle, transverse at the ends. 

 — Vega p. 464 PL XXXV f. 19. 



Marine: Cape Deschneff! 



Stauroneis delicatula Leud. Foktm. (Ceyl. p. 36 PL III f. 34, 1879) is twice as large as 

 N. megastauros and seems to be akin to it. I have not seen this species. 



8. N. halionata Pant. (1886). — V. lanceolate, gradually tapering from the middle to the 

 obtuse ends. L. 0,i2 to 0,22; B. 0,03 to 0,o48 mm. Area broad, lanceolate. Strise 8 to 9 in 0,oi 



