KONGI/. SV. VET. AKADEMIENS HANDLINGAR. BAND. 27. N:0 3. 67 



Thus, it appears that the forms of the la'vistriatfB are intermediate between the Pinnulariaj and 

 the true Naviculse. 



The species of this group are usually inhabitants of brackish water and sestuaries. but 

 there are also purely marine forms among them. 



Artificial hey. 



I 



J . Valve sigmoid .... . ... . ... X Raeana Caste. 



straight . . . . . 2. 



„ I Axial area abruptly dilated into an orbicular central area or transverse fascia ... 3. 



\ Axial and central area uniting into a lanceolate or linear space 7. 



., I Median strise of equal length . . . 4. 



1 — — alternately longer and shorter . ... .... X. lauta Grun. 



Central area orbicular . . . 5. 



— — a transverse fascia . ... 6. 



M 



I Valve acute or rostrate . xV. elegans W. Sm. 



I — obtuse X. Chyzerei Pant , N. discernenda Pant., N. grata Pant. 



^ j Valve large. L. about 0,06 mm X. bituminosa Pant. 



\ — small. L. about 0,02 mm. . . . . X. megastauros Cl. 



„ J Valve triundulate .... X. Areschougiana Geun. (N. palpebralis r. Botteriana Grun.). 

 ■ t — not — 8. 



„ , Striae radiate throughout . .... . 9. 



Terminal striae convergent or parallel . ... 12. 



„ ( Median striae of equal length . . .... 10. 



' \ — — alternately longer and shorter . . 11. 



-„ j Area very broad N. marginulata Cl. 



\ — medium sized X. palpebralis Bbeb. 



Area narrow X. Vahliana Gk0N. 



— rhombic-lanceolate N. solida Cl. 



Valve elliptical N. Kochii Pant. 



"•{ 



(Vail 



) — lanceolate 13 



.,„ ( Strise coarse, distant, 4 to 8 in 0,01 mm X. yarrensis Geun. 



' ■ \ — closer, 8 to 9 in 0,01 mm X. halionata Pant. 



1. N. bituminosa Pant. (1889). — V. linear-lanceolate, with subacuminate ends. L. 0,o65; 

 B. 0,0 145 mm. Central pores of the median line somewhat approximate. Axial area narrow, linear. 

 Central area a broad suborbicular fascia, almost reaching the margin. Strige 10 in 0,oi mm., 

 divergent in the middle, convergent at the ends. — Pant. II p. 42 PI. VII f. 137. 



Brackish water: Hungary fossil! 



Var. latecapitata Pant. (1889). — V. linear, with broad, rostrate ends. L. 0,o64; B. 0,oi35 

 mm. Striae 8,5 to 9 in 0,oi mm. — Pant. II 1. c. f. 133. 



Brackish water: Gyongyos Pata, Hungary fossil (Pant.). 



Var. robvsta Pant. (1889). — V. with capitate-rostrate ends. L. 0,08.5; B. 0,oi8 mm. Cen- 

 tral area lanceolate. Strise 10 to 11 in 0,oi mm. — Pant. II PI. XI f. 202. 



Brackish water: Erdobenye, Hungary, fossil (Pant.). 



Var. signata Pant. (1889). — V. linear-lanceolate, with obtiise ends. L. 0,o68; B. 0,oi8 mm. 

 Central area a transverse fascia reaching nearly to the margin. Stria?. 11 to 12,.t in 0,oi mm. — 

 Pant. II p. 43. N. bit. v. valida PI. V f. 89. 



Brackish water: G-yongyos Pata, Hungary, fossil (Pant.). 



Var. staurophora Pant. (1889) — V. lanceolate. L. 0,o54 to 0,075; B. 0,oi3 to 0,oi5 mm. 

 Central area a broad fascia, reaching to the margin. Striae 10 to 11 in 0,oi mm. — Pant. II 

 PI. V f. 87, 88. 



Brackish water: Hungary fossil (Pant.). 



Var.? cificta Pant. (1889). — V. lanceolate, with obtuse ends. L. 0,075; B. 0,016 mm. 

 Area lanceolate, very wide. Striae 12,5 in 0,oi mm. — Nav. cincta Pant. II p. 44 PI. XI f. 196. 



Brackish water: Hungary, fossil (Pant.). 



