68 p. T. CLEVE, SYNOPSIS OF THE NAVI('L;L( »11) DIATOMS.- 



N^((r. hitKniiiiosd i.s a variable species, which is chjseiy akin to I'lnuuluriu, section (liocrgiiitea. 

 (Jn the otlier hand some of its varieties, seem to be akin to varieties of Nav. Yarrcnsis. The areas 

 are subject to great vai'iation, and tliere are gradual passages from forms with 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. cinda Pant,, ivhich 1 know onl^- by the figure in 

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

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



2. N. <'liyz<'i*eii Pant. (1889). — V. elliptic-lanceolate, with obtuse extremities. L. 0,(phh; 

 B. (l,()i'.i mm. Axial area distinct, linear, abruptly dilated to an orbicular central area. Strise S 

 to 10 in 0,111 mm. divergent in the middle, convergent at the ends. — Pant. 11 p. 43 PI. Y f. iHi. 



Brackish water: Hungary, fossil! 



3. N. discernenda Pant. (1889). — V. linear-elliptical, with subcuneate ends. L. o.o.i- to 

 0,05; B. 0,0 12 to 0,(11 ;5 mm. Axial area very narrow; central area large, orbicular. Stria'- 12 to 

 14 in 0,0 1 mm. divergent in the middle, convergent at the ends. — Pant. II p. 45 PI. XXll f. 335. 



Brackish water: Hungary, fossil! 



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

 somewhat closer stria?. 



4. N. grata Pant. (1889). — V. narrow, ellijjtic-lanceolate. L. 0,o84; B. 0,oi.'i mm. Median 

 pores distant. Axial area narrow linear, strongly dilated in the middle. Stria^ 11 in 0,01 ram., 

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

 p. 46 PI. 11 f. 21. 



Brackish Avater: Hungary, fossil (Pant.). 



5. N. elcgaiis 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. Striye 9 in 0,oi mm., strongly divergent in the middle, convergent 

 at the ends. — Br. I). 1 p. 49 PI. XVI f. 137. Donk. Br. I), p. 23 PI. IV f. 1. 



Marine to brackish: England! Bohuslan! 



Var. cuspidata Cl. — V. rostrate. L. 0,o8; B. 0,02 mm. Striju closer, altout 12inO,iii mm. 



Brackish water: Atlantic coast of North America! 



6. N. laiita (Irun. (1888). — V. linear-elliptical, with subcuneate ends. L. 0,u95; B. 0,028 

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

 contrary directions ((Irnn.). Stria- 13 (9 to 10 Grun.) in 0,01 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 PI. I f. 30. 



Brackish water: South Yarra, Australia! 



7. N. luegastauros Ol. (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 1(3 in 0,(ii mm., strongly divergent in the middle, transverse at the ends. 

 -- Vega p. 464 PI. XXXV f. 19. 



Marine: Cape Deschneff! 



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

 N. megnstaiiros 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, 12 to 0,22; B. 0,o;s to 0,048 mm. Area broad, lanceolate. Striai 8 to 9 in 0,oi 



