KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 27. N:0 3. 21 



24. N. oblonga Kutz (1833). — V. linear-lanceolate, witli truncate ends. L. 0,07 to 0,2; 

 B. 0,014 to 0,024 mm. Axial area very narrow. Central area suborbicular. Strise 7 to 8 in 0,oi 

 mm., very finely lineate, the median more distant and strongly radiate, the terminal convergent 

 and angularly bent. — Frustulia oblonga KtJTZ Dec. N:o 71 (accord. to Lägst.). N. oblonga KtJTZ 

 Bac. p. 97 Pl. IV f. 21. Grun. Verh. 1860 p. 523. A. S. Atl. XLVII f. 63 to 68. V. H. Syn. 

 p. 81 Pl. VII f. 1. Pant. Ill Pl. VIII f. 142. Pinnul. oblonga W. Sm. B. D. XVIII f. 165. 



Fresh or very slightly brackish water: Sweden! Finland! Saxony! Belgium (V. H.), Eng- 

 land! Switzerland (Brun.), Illinois! Fossil: Dubravica, Hnngary (Grun.), Mexico and Guatemala! 



Var. lanceolata Geun. (1860). — Shorter and broader lanceolate. — Verh. 1860 p. 523 

 Pl. IV f. 25. 



Var. acuminata G-run. (1860). — Almost linear, with cuneate, obtnse ends. — 1. c. 



Fresh water: Austria (Grun.). 



Var. nodulosa Grun. (1860). — As the var. acuminata, bnt with triundulate margins. — 1. c. 



Fresh water: Frankfurt am Main. 



25. N. falaisiensis Grun. (1880). — V. narrow, lanceolate, with subrostrate, obtuse ends. 

 L. 0,02.5; B. 0,005 mm. Axial area indistinct. Central area small, rounded. Striee about 20 in 

 0,01 mm., slightly radiate throughout. — V. H. Syn. Pl. XIV f. 5. 



Fresh water: Greenland! England (V. H. T.), Belgium (V. H.). 



Var.? Lanceola Grun. (1880). — V. linear with more distinctly rostrate ends. L. 0,o3; 

 B. 0,004 mm. Strise 23 in 0,oi mm. more radiate — V. H. S. Pl. XIV f. 6 B. 

 N. falaisiensis is according to Grunow nearly related to N. Bulnheimii. 



26. N. arenicola Grun. (1882). — V. linear, frequently slightly gibboiis in the middle, 

 with broad, rounded ends. L. 0,02; B. 0,oo5 mm. Axial and central areas indistinct. Strise 13 

 or 14 (middle) to 21 (ends) in 0,oi mm. very finely lineate, slightly radiate throughout. — Ämphi- 

 prora arenaria Bréb. in Rab. A. E. N:o 2150. N. arenicola Grun. F. D. Öst. Ung. p. 149 

 Pl. XXX f. 76, 77. 



Marine (aestuaries); Coasts of France and England (Grun.). Firth of Tay! 



27. N. dicephala (Ehb. 1836?) W. Sm. (1853). — V. linear to linear-lanceolate with capi- 

 tate-rostrate ends. L. 0,025 to 0,04; B. 0, 01 to 0,0125 mm. Axial area indistinct. Central area 

 large, transverse and rectangular. Striee 9 to 11 in 0, 01 mm. radiate throughout. — Fin. diceph. 

 Ehb. Inf. p. 185. Am. II: 1 f. 29? N. dicephala W. Sm. B. D. I p. 87 Pl. XVII f. 157. Grun. 

 A. D. p. 34. V. H. Syn. p. 87. Pl. VIII f. 33, 34. Ströse Klicken D. i. 4. 



Fresh water: Sweden! England! Saxony! Switzerland (Brun.), Hungary, Dubravica, fossil 

 (Grun.), Kamtchatka! Japan! Illinois! Ecuador! 



Var. elginensis Greg. (1856). — L. 0,024 to 0, 03; B. 0, 01 to 0,oio5 mm. Strise 12 to 14 in 

 0,01 mm. transverse at the ends. — Pinn. elginensis Greg. M. J. IV Pl. I f. 33. Grun. A. D. p. 35. 



Fresh water: Scotland, Ben Lawers fossil (Grunow), Finland, Pudasjärvi, fossil! 



Var. subcapitata Grun. (1882). — V. with broadly truncate ends. — F. D. Öst. Ung. p. 156 

 Pl. XXX f. 54. 



Fresh water: Hungary, fossil (Grun.). 



N. dicephala is very nearly connected with the Cymbellse, which, besides its great resem- 

 blance to Cym. anglica, is proved by its cell-coutents (see A. S. Atl. Pl. LXXII f. 29 — 33; Grun. 

 F. D. Öst. Ung. XXX f. 55). There is only one chromatophore-plate, in the middle separated 

 by a plasmatic mäss from the zone, and on the dorsal side deeply cloven by a linear fissure. 



28. N. lanceolata (Ag. 1827?) Kutz (1833). — V. lanceolate. L. 0,o3 to 0,05; B. O.oos to 

 0,01 mm. Axial area indistinct. Central area distinct, orbicular. Strise 12 (middle) to 15 or 16 

 (ends) in 0,oi mm., strongly radiate throughout. — Frustulia lanceolata Agardh Flora X p. 626? 



