A. CLEVE-EULER, DIAT. FLORA OF FINLAND. 17 



Foss. : Kk. Knjäsha. 



Some small, hyaline valves with a stauroid marking across 

 the middle are possibly identical with this species. 



Navicula (Libellus) plicata Donk. B. D. Tab. 9, f. 2. 

 Cleve, Syn. Nav. D. I, p. 154. 



Foss.: Sat. Panelia, rare. 



Distr. {7nar.): East Arctic Sea, North Sea, Baltic, Medi- 

 terranean, Labuan, Brezil. 



Navicula (Libellus?) Klavsenii östr. var. turgida n. var. 

 — PI. 1, f. 14 a, b. 



Valve lanceolate, fusiform, gradually tapering towards 

 the narrow, rounded ends, very convex. Length 70 [J., breadth 

 15 |J.. Striae fine, apparently smooth, parallel, equidistant, 

 17 in 10 {A. Axial area indistinct, central area small, circular. 



Foss.: Kk. Knjäsha, rare. 



Distr. of the main form [mar.): E. Greenland (0'strup, 

 Färskv. D. 0st-Gr0nl., p. 281, Tab. 1, f. 13). 



The Finlandian form, of which I give a figure in as well 

 valvar as zonar view, agrees in all respects, except in the 

 breadth of the valve being twice as large, with the Navicula 

 Klavsenii described by 0strup from East Greenland. As 

 to the nearest affinities of this species, I have been hesit- 

 ating between the groups of the Naviculae Entoleiae Cl. and 

 the Libelli. The convex, fusiform shape of the valve and 

 the fine, parallel striae recall Navicula inornaia Grun. among 

 the former, but there is no lanceolate axial area as in this 

 species. On the other hand, though the convex valves re- 

 semble those of a Libellus, the striation is rather different, 

 no puncta being visible. Were it not for the smooth striae, 

 it would seem closely allied to Libellus ^plicata. Perhaps the 

 nearest relations, thus, are to be found elsewhere, or among 

 the Naviculae Fusiformes Cl. (Syn. Nav. D. I, p. 105), though 

 the species of this group have no central area. 



Navicula (Scoliopleura) tumida Bréb. — V. H. Syn. 

 Tab. 17, f. 11, 13. 



Foss.: Sat. Panelia (rare); Kk. Knjäsha, Koudajärven- 

 pää, frequent. 



Arkiv för botanik. Band Ii. N:o 9. 2 



