24 ARKIV FÖR BOTANIK. BAND 14. NIO 9. 



20 a in length, 6 [x in breadth. Areas indistinct. Striae 

 slightly radiate, at the ends transverse, c. 18 in 10 a. 



Foss.: Kk. Knjäsha {marine dep.). 



0STRUP gives in Mar. D. 0st-Gr0nl. Tab. 4, f. 30 a figure 

 of a small form, that I believe identical with the present one. 

 Mr 0STRUP refers it, with hesitation, to Navicula hahusiensis 

 Grun., but I cannot join him in this determination, as the 

 latter is a broad, obtuse species. I believe in contrary iVa- 

 vicula ammophila to be the nearest relation, as this species 

 has acute ends and a similar striation. 



Navicula cancellata Donk. var. subapiculata Grun. — 

 A. S. Atl. Tab. 46, f. 66—68. Icon. nost. PI. 1, f. 19. 



Foss.: Kk. Knjäsha. 



Distr. {mar.): Greenland (0strup), East Arctic Sea, 

 Baltic, Firth of Tay. 



In PI. 1, f . 25 b I have drawn a frustule in zonar view, 

 showing the convex valves and the very narrow connecting 

 zone. • 



Navicula cancellata Donk. var. retusa Bréb.? — V. H. 

 Syn. Suppl. A, f. 9. — Icon. nost. PI. 1, f. 20. 



Foss.: Kk. Knjäsha. 



Distr. (mar.): Greenland (0strup), East Arctic Sea, North 

 Sea; ubiquist. 



Some Finlandian specimens (cfr. the fig.) have are mark- 

 ably large, circular area. 



I have also observed a frustule with very convex valves, 

 that in zonar view is exactly similar to Donkin's figure of 

 Navicula fortis Greg. (B. D. Tab. 8, f. 8 c), but as I have 

 not seen the valves in front view, I cannot warrant the 

 identity. 



Navicula distans (W. Sm.) B. D. Tab. 18, f. 169. V. H. 

 Syn. Suppl. A, f. 18. 



Foss.: Kk. Knjäsha, Koudajärvenpää, not rare. 



Distr. (mar.): Greenland, East Arctic Sea. 



According to Cleve (Syn. Nav. D. II, p. 35), this species 

 is characteristic to the Arctic Sea and Northern Atlantic. 



