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



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

 B. 0,014 to 0,02 4 mm. Axial area very narrow. Central area suborbicular. Striae 7 to 8 in 0,oi 

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

 and angularly bent. — Frustulia ohlonga KUtz Dec. N:o 71 (accord, to Lagst.). N. ohlonga KCtz 

 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 PI. VII f. 1. Pant. Ill PL VIII f. 142. Pinnul. ohlonga W. Sm. B. D. XVIH f. 165. 



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

 land! Switzerland (Brun.), Illinois! Fossil: Dubravica, Hungary (Glrun.), Mexico and Guatemala! 



Var. laneeolata Grun. (1860). — Shorter and broader lanceolate. — Verh. 1860 p. 523 

 PL IV f. 25. 



Var. acuminata Grun. (1860). — Almost linear, with cuneate, obtuse ends. — 1. c. 



Fresh water: Austria (Grun.). 



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



Fresh water: Frankfurt am Main. 



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

 L. 0,025; B. 0,00.') mm. Axial area indistinct. Central area small, rounded. Striae about 20 in 

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



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



Var.? Lanceola Grun. (1880). — V. linear with more distinctly rostrate ends. L. 0,03; 

 B. 0,004 mm. Striae 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 gibbous in the middle, 

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

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

 prora arenaria Br:^b. in Eab. A. E. ]SI:o 2150. N. arenicola Grun. F. D. Ost. 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,oi to 0,0125 mm. Axial area indistinct. Central area 

 large, transverse and rectangular. Striae 9 to 11 in O,oi«mm. radiate throughout. — Pin. diceph. 

 Ehb. Inf. p. 185. Am. 11: i 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. Strose Klieken D. f 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,oi to 0,oi05 mm. Striae 12 to 14 in 

 0,01 mm. transverse at the ends. — Finn, elginensis Greg. M. J. IV PL If. 33. Grun. A. D. p. 35. 



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



Var. suhcapitata Grun. (1882). — V. with broadly truncate ends. — F. D. Ost. 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-contents (see A. S. Atl. PL LXXII f. 29 — 33; Grun. 

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

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



28. N. laneeolata (Ag. 1827?) KtiTZ (1833). — V. lanceolate. L. 0,o3 to 0,05; B. 0,oo8 to 

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

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



