KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 26. N:0 2. 139 



radiate; terminal stri<3e 13 in 0,oi mm., slightly convergent; all finely punctate. — Ehb. Am. I: 2, 

 f. 17. M. G. XVI, I f. 11? W. Sm. B. D. I p. 50 PL XVI f. 141. Donk. B. D. p. 21 PI. Ill 

 f. 8. A. S. Atl. LXXII f. 1. Gkun. Franz Josephs Land D. p. 99 (47) PL I f. 34. AmpMprora 

 navicutaris Ehb. Micr. G-. Ill: i, f. 10, 11. 



Fresh water: Franz Josephs Land (Grun.), Sweden (Lule Lappmark living, common in post- 

 glacial, lacustrine deposits)! Finland, foss.! England (Hull) Donk., G-ermany, Harz (Atl.); Bohemia, 

 Eger fossil! North America: common in diatomaceous earths (Nova Scotia, Canada West, Wash- 

 ington territory etc.)! 



What Nav. Semen of Ehrenberg may denote is impossible to decide, as the figures published 

 by Ehrenberg cannot be recognized. The figure in W. Smith Brit. Diat. is not good, but leaves 

 little doubt that the author meant the same species, which now is generally believed to be N. Semen. 

 On the other hand there can be no doubt that AmpMprora naviculoides of Ehrenberg is the same 

 species as our N. Semen. N. Semen seems to be a northern species, rarely found living, but fre- 

 quently in postglacial deposits of Scandinavia and North America. It is not mentioned by Brun 

 as an inhabitant of the Alps, nor by Belloc as occurring in the Pyrenees. Its occurrence in a 

 living state in the Harz is an interesting fact and suggests that it may be a survival from the 

 post-glacial epoch. 



2. N. (Biadesmis) seminoides Cl. & Grove N. Sp. — V. elliptic-lanceolate, with truncate 

 ends. L. 0,027 to 0,045; B. 0,oi to 0,oi2 mm. Axial area narrow linear, suddenly dilated to a 

 small, orbicular central area. Striae in the middle 16 in 0,oi mm., alternately longer and shorter, 

 divergent; strise at the ends about 23 in 0,oi mm. slightly convergent, all finely punctate. 



Slightly brackish water: West Indies, Jamaica (Grove Coll.)! Ecuador! 



This small form resembles in outline N. Semen. The frustules form in living state coherent 

 filaments. 



3. N. brasiliana Cl. (1881). — V. lanceolate, with subacute ends, often slightly asymmetrical. 

 L. 0,035 to 0,065; B. 0,oi2 to 0,0 18 mm. Median line straight; its terminal fissures in the same 

 direction. Axial area narrow, linear, somewhat dilated around the central nodule. Strise in the 

 middle 18 in 0,oi mm, divergent alternately longer and shorter; towards the ends 21 to 22 in 

 0,01 mm.; at the ends convergent; all distinctly punctate; puncta (on the median strise about 18 

 in 0,01 mm.) forming undulating, longitudinal rows. — Cynihella brasil. Cl. N. R. D. p. 4 PL I f. 4. 



Fresh water: Brazil! Calif. (St. Rosa in Grove Coll.)! Ecuador in mineral springs at Tesalia 

 Prov. Pichincha! 



4. N. inflata .Donk. (1870). — V. lanceolate with capitate ends. L. 0,022 to 0,o26; B. 0,oo7 

 to 0,008 mm. Axial area indistinct, central area small, irregular. Strise in the middle 19 in 0,o] 

 mm., somewhat divergent and of unequal length; other strise 22 to 23 in 0,oi mm., convergent at 

 the ends, all indistinctly punctate. — Donk. B. D. p. 21 PL III f. 9 (nee Kiitz. = X. hunyarica?) 

 Cl. D. of Finl. p. 37 PL II f. 2 (1891). 



Fresh water: Ireland (Lough Mourne foss. Donk.), Sweden (Lake Rosslangen in Kalmar 

 Ian, Rimforsa in Westergotland) ! Finland, foss.! N. America (Houghton, Michigan, foss.)! 



5. N. ramphoides Pant. (1889). — V. narrow, rhombic-lanceolate, with acute ends, very 

 convex. L. O.ose to 0,09; B. O.oia mm. Median line with approximate central pores. Axial area 

 indistinct. Central area (by the distant median strise) a narrow transverse fascia. Striae about 

 14 in 0,01 mm. (the median more distant) very slightly radiate, at the ends transverse, indistinctly 

 punctate. — Pant. II p. 53 PL V f. 97, 98. 



Brackish water: Hungary, fossil! 



6. N. Crucieula W. Sm. (1853). — V. lanceolate to elliptic-lanceolate, with somewhat obtuse 

 ends. L. 0,04 5 to 0,o7; B. 0,015 to 0,oi9 mm. Central nodule transversely dilated. Axial and 



