FRESH-WATER DIATOMS FROM ICELAND 65 



Cyclotella comta (Ehr.) Ktz. V. H. Tit. 446, Tab. XXII, fig. 653. 

 Ostenf. Thingv. 1115, Tab. I, figs. 9—10. 

 Thingvallavatn S.W. C. H. O. 

 Area: Eur.. Af., As. 

 Found by C II. Ostenfeld, not by myself. 



Cyclotella Kützingiana Chauvin. V. H. Tit. 447, Tab. XXII, fig. 657. 

 18 samples S. 1, SW. 3, X. 1, E. 13). 

 Area: Eur., Af, As. 



Cyclotella Meneghiniana Ktz. V. H. Tit. 447, Tab. XXII, fig. 656. 

 6 samples (S.W. 5, E. 1). 

 Area: Eur., Af., As., Am. 



Stephanodiscus (Ehr. 1845) Grun. emend. 1880. 



Stephanodiscus Astræa (Ehr.) Grun. Cl. & Gr. A. D. 114. V. H. 

 Syn., Tab. XCV, lig. 5. 

 Krisuvik (S.) C. H. O. 

 Area: Eur., Af., As., Grl.. Fz. J. 



The following are forms of fresh -water Diatoms (including a 

 few forms from brackish water) not found again by me, but by 

 other Diatomologists, without their having definitely localised them. 



Ceratoneis Arcus (Ehr.) Kütz. var. amj>hio.vijs Rabh. Rabh. Süssw. 

 37, Tab. IX, fig. 4. Found by Relloc. 



Cyclotella minutissima. Unknown to me. Perhaps identic with 

 Cyclotella minutula Ktz. = Stephanodiscus Astræa (Ehr.) Grun. var. 

 minutulus (Ktz.) Grun. V. H. Syn. CXCV, figs. 7 — 8 or with Cyclo- 

 tella operculata (Ag.) Kütz. var. minutula (Ktz.) Br. Brun Diat. Alp. 

 & Jura 133, Tab. I, fig. 7. F. b. E. Belloc. 



Cymbella norvegica Grun. Cl. Syn. I, 169. A. S. Atl., Tab. X, fig. 

 41. F. b. P. T. Cleve. 



This Cymbella is very closely related to C. gracilis Rabh. (enfr. CI: 

 1. c.) and is hardly a dillerent species. 



Denticula obtusa W. Sin. W. Sin. Syn. II, 10, Tab. XXXIV, fig. 

 292. F. b. E. Belloc. 



This species is without doubt identical with Nitzschia Denticula Grun. 



Gomphonema geminatum Lyngb. Cl. Syn. 1, 186. V. H. Trt., Tab. 

 XXIX, lig. 10. F. b. E. Belloc. 



The Botany of Iceland. Vol II. 5 



