66 ARKIV FÖR BOTANIK, BAND H. N:0 9. 



Cyclotella bodanica Eulenst. var. borealis A. Cl. Cycl. 

 bod., p. 441, f. 2 c. 



Foss.: Kk. Knjäsha, rare. 



Distr. {fresh w.): Lakes of Northern Sweden. 



A few specimens with 2 — 3 channels were met with among 

 chiefly marine remains. 



Cyclotella (Kützingiana var.? ) abnormis n. var. — PI. 

 3, f. 69. 



Foss.: Ab. Hindersmossen. 



As the form figured is somewhat abnorm, with some of 

 the radiate striae perforated, I do not venture to give it a 

 name. Perhaps it is a form of Cyclotella Kützingiana. 



Cyclotella dubia Fricke, A. S. Atl. Tab. 223, f. 23, 25. 

 — Syn. Stephanodiscns pulcherrimiis A. Cl. Arch. f. Hydro- 

 biol. Bd 6 (1910), p. 211, f. 3. —Icon. nost. PL 3, f. 70 a— d 



Foss.: Kk. Tuntsa; Ab. Hindersmossen. 



Distr. {fresh iv.): Limnetic in European lakes, especially 

 when small and shallow. 



As I have remarked in the paper quoted above, this 

 species can be referred to the genus Cyclotella as well as to 

 Stephanodiscns. It has the characters of the former, viz. a 

 marginal zone with a special structure, but the loculi some- 

 times are small, the whole valve then getting very similar 

 to that of a Stephanodiscns. 



I have found this small species to be spread in many 

 Swedish lakes as well as in fossil deposits, and it may no 

 doubt in the future be recorded living also in Finlandian lakes. 

 From Steph. astraea it is easily distinguished by the single 

 rows of rather coarse puncta. In a fossil state, the valves 

 generally have the aspect shown by fig. 70 d. 



Cyclotella dubia Fricke var. spinulosa n. var. — PI. 3, 

 f. 71. 



Differs from the type by the presence of delicate thorns 

 inserted between every second alveolus. 



Distr. {fresh w.): sparingly among the type. 



