56 ARKIV FÖR BOTA^•IK. BAND U. N:0 0. 



Distr. {jresh iv.): Lule Lappmark, Germany, Süd-Pata- 

 gonien. 



This form, that I am unable to distinguish from Fragi- 

 laria lancettiila Schum., occurred in a purely marine sample. 



Fragilaria mutabilis (W. Sm.) var. elliptica (Schum.) 

 Carls. — V. H. Syn. Tab. 45, f. 15—17. — A. S. Atl. Tab. 

 297, f. 55—58, 65—68, 70—72. 



Foss.; Ab. Hindersmossen, with the main form. Probably 

 very spread. 



Distr. {fresh w.): Europe, Asia. 



Fragilaria parasitica (W. Sm.) Grux. — V. H. Syn. 

 Tab. 45, f. 30. 



Foss.: Ab. Hindersmossen. 



Distr. {fresh and brack, w.): Europe, Asia, Africa. 



Fragilaria producta Lagst.? — A. S. Atl. Tab. 297, f. 73 

 — 76. — Icon. nost. PI. 4, f. 95 a, b. 



Foss.: Kk. Knjäsha, rare. 



Distr. {fresh w.) : Spitzbergen, Lapland. 



Some frustules in a chain, 13 a in length, with elongated- 

 elliptical valves, 4,5 a in breadth. Striae 15 in 10 a, parallel, 

 interrupted by a very narrow, but distinct, pseudoraphe. 



Though occurring in a marine sample, this form Avas de- 

 termined to Fragilaria producta, because I cannot find any 

 difference between it and the species of Lagerstedt, as 

 figured in Schmidt's Atlas by Hustedt. On the other hand, 

 it may possibly belong to the marine small species Fragilaria 

 arctica Grun. figured in Arct. Diat. Tab. 7, fig. 124, from 

 which it differs only by the presence of a pseudoraphe. 

 Grunow's figure shows no axial area, but the texte (A. D., 

 p. 110) states a faint raphe to be present in the species. 



Thalassiotlirix Cl. and Grun. 



Thalassiothrix nitzschioides Grux. — V. H. Syn. Tab. 

 43, f. 7. Xord. Plankton, p. 117, f. 159. 

 Foss.: Kk. Knjäsha. 

 Distr. {mar.): North Sea, Atlantic. 



