MARINE DIATOMS FROM THE COASTS OF ICELAND 369 



Sigmata Grun. 1880. V. H. Trt., 396. 



Nitzschia Sigma W. Sin. V. H. Trt., 396, Tab. XVI, fig. 531. 



12 samples (S.I, S.W. 8, N.I, E. 2). 

 Area: Ubiquist, Grl., A. S. 



Nitzschia Sigma W. Sm. var. rigida (Ktz.) Grun. V. H.Trt., I.e., 

 fig. 533. 



BiitMr (S.W.), H.Js. 

 Area: Eur., Afr. 



Lineares Grun. 1880. V. H. Trt., 398. 



Nitzschia vitrea Norman var. Salinarum Grun. V. H.Trt. ,399, 

 Tab. XVI, fig. 546. 



Njardvik (S.W.), C. H. O. 

 Area: Eur. 



Lanceolatce Grun. 1880. V. H. Trt., 400. 



Nitzschia lanceolata W. Sm. V. H. Trt., 400, Tab. XVII, fig. 548. 

 Reykjavik (S.W.), B. S. 



Rhopalodia O. Miiller 1895. V. H. Trt., 307. 



Rhopalodia Musculus (Ktz.) O. M. V. H. Trt., 297, Tab. IX, fig. 359. 

 (Epithemia Muse.) 



Steingrimsfjordur (X. 3 samples), H. Js. 



Arraphideae 



Synedra Ehr. 1831. V. H. Trt., 307. 



Synedra affinis Ktz. V. H. Trt., 314; Per. D. mar., 318. 



I have found Synedra affinis with variants as delineated in V. H. Syn., 

 tab. XLI, in Per. D. mar., tab. LXXX, and in A. S. Atl, tab. CCCIV, in all 

 in 184 samples (S. 13, S.W. 77, N.\V. 27, N. 50, E. 17). 



Of the numerous variants, difficult to distinguish from each other, 

 I have noted the following: 



Synedra affinis var. gracilis Grun. V. H. Syn., Tab. XLI, fig. 15 B. 



Area: Eur., Grl. 



Synedra affinis var. fasciculata Ktz. V. H. Syn., 1. c., fig. 15. 



Area: Eur., As., Grl., A. S. 



Synedra affinis var. lancettula Grun. V. H. Syn., 1. c., fig. 28. 



Area: Am., Grl. 



Synedra affinis var. parva Ktz. V. H. Syn., 1. c., fig. 23. 



Area: Eur., Afr., Aust., Grl., A. S. 



