FRESH-WATER DIATOMS FROM ICELAND 49 



Nitzschia vitrea Norman var. recta Hentzsch. V. H.Trt.400, Tab. 

 XVI, fig. 547. 



Ulfjölsvatn (S.) A. F. 

 Area : Eur., As., Am., Grl. 



Var. Salinarum Grim. V. H.Trt. 399, Tab. XVI, fig. 546. 

 Arnafellskvisl (S.) St., Vcstmannaeyjar (S.) St. 

 Area : Eur. 



In Denmark I have found the identical form in fresh-water (cnfr. 

 Øst. I). I). 161). 



Nitzschia Oestrupi Pant. Pant. Lac. Peis. 30, Tab. Ill, fig. 145. 

 Arnafellskvisl (S.) St., Skaptafellssysla (S ) St. 



Pantocsek (1. c.) refers this species to a new section "Constrictae". 

 I think it might very well be placed under "Lineares", closest to N. Kittli. 



Lanceolatœ Grun. 1880. V. H. Trt. 400. 



Nitzschia amphibia Grun. V. H. Trt. 403, Tab. XVII, fig. 563. 

 55 samples (S. 14, S.W. 17, N. 11, E. 12, s. 1. 1). Hot springs: 17. 

 Area: Eur., Af, Am. 



Var. acutiuscula Grun. Cl.&Gr. A. D. 98. V. H. Syn., Tab. LXVIII, 

 figs. 19—22. 



Laugarvatn (S.) A. F. 

 Area: Eur., Am., Aust. 



Var. Frauenfeldi Grun. CI. &Gr. A.D. 98. V. H. Syn., Tab. c, fig. 18. 

 12 samples (S. 4, S.W. 4, N. 2, E. 2). Hot spring: 1. 

 Area: Eur., Am., Aust. 



Nitzschia Frustulum (Ktz.) Grun. V. H. Trt., 403, Tab. XVII, fig. 564. 



6 samples (S. 3, N. 1, E. 2). Hot spring: 1. 

 Area: Eur., Af., Am., Grl., J. M., Spb., Fz. J. 



Nitzschia glaberrima sp. now, Tab. nost. V, fig. 73. 



Long: 04 /u, lat: 3 //. 



Valva lineari, apicibus subcapitatis. Structuram ullam valvæ per- 

 spicere non potui. Una in margine valvæ autem puncta minutissima 

 et innumerabilia adsunt. 



Reykjavik (S.W.) H. Js. 



I consider this form must be placed under "Lanceolatæ" possibly 

 nearest to Nitz. gracilis. 



Nitzschia Hantzschiana Rbh. var. glacialis Grun. CI. & Grun. A. D. 

 99. V. H. Syn., Tab. LXIX, fig. (N. Frust. glac). 



7 samples (S.W. 5, E. 2). 

 Area: Eur., Grl., Spb., Fz. J 



The Botany of Iceland. Vol. II. 4 



