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maz. F. construens (Ehrbg.) Grun. (mostly f. binodis (Ehrbg.) Grun). 

 Diatoma hiemale (Lyngb.) Heib. Melosira granulata (Ehrbg.) Ralfs, 

 f. cur vat a Grun. M. varians Ag. 



The bottom forms were numerous; some of them were 

 rather common, e. g. Cymbella cistula (Hempr.) Kirchn., and C. 

 ventricosa Ag., Gomphonema sp., Meridion circulare (Grev.) Ag. 

 and Amphora ovalis (Bréb.) Kütz; other occurred more sparingly, e. g. 

 Epithemia turgida (Ehr.) Kütz., Rhopalodia gibba (Ehrbg.) 0. Müll., 

 Cymatopleura elliptica (Bréb.) W. Sm., C. solea (Bréb.) W. Sm., 

 Cymbella aspera Ehrbg., Finnulària major Kütz., Stauroneis acuta 

 W. Sm., Cocconeis placentula Ehrbg. etc. 



Fig. 1 Diatoma hiemale (Lyngb.) Heib. Part of a band, showing numerous 

 chromatophores and oildrops. ( 450 /i.) 



Fig. S. Fragilaria capucina Desmaz. Part of a band, showing the chromato- 

 phores. ( 450 /,.) 



Fig. 3. Fragilaria construens (Ehrbg.) Grun., f. binodis (Ehr.) Grun. Part of a 



band, showing the chromatophores. ( 450 /i). 

 Fig. 4. Melosira granulata (Ehrbg.) Ralfs., f. curvata Grun. A strongly screwed 



band. ( J00 /,.) 



Fig. 5. Melosira granulata (Ehrbg.) Ralfs., f. curvata Grun. Part of a band, 

 showing the 5 chromatophores and the large oildrops. ( 450 /i.) 



With regard to the plankton forms it is of interest to see Dia- 

 toma hiemale occurring limnetic; it forms long bands just like a 

 Fragilaria. So far as I know, this form has not before been no- 

 ticed as a plankton diatom; but it is a form which is charac- 

 teristic for cold water in arctic and alpine countries. I have given 

 a figure (fig. 1) of a part of a band showing the coccochromatic 

 chromatophores together with oildrops. Also of the two common 

 Fragilaria-îorms (figs. 2 and 3) I have figured some cells with 

 contents. 



3 



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