The diatoms, living in the arctic sea are relatively very 

 little known, ouly one enumeration of forms observed in samples 

 from Spetsbergen having been published by me in the Öfvers. 

 af K. A^et. Akad. Förh. 1867 (sid. 661). This catalogue is by 

 no means complete, as the materials for my researches were 

 somewhat scarce and my experience in determining the species 

 ■at that time not very great. Scarcely more than 40 marine 

 species are enumerated in my paper quoted above. 



Since that time I have had through the several Swedish arctic 

 expeditions to Spetsbergen and Greenland an opportunity of 

 examining a more complete collection of samples, partly taken 

 on the surface of the sea between Europé and Greenland as 

 well as from Davis Strait and collected by Mrss. Th. Fries, 

 P. Öberg and Lindahl, and partly deposited on the bottom of 

 the bottles, in which had been preserved smaller arctic ma 

 rine animals. 



The diatoms of the arctic sea form together a somewhat 

 peculiar flora, certainly having many species in comlnon with 

 that of the tropical seas, but still distinguished by the frequent 

 occurrence of several forms, not found in the southern seas, 

 as well as by the absence of forms rarely absent in any ma- 

 rine mnd from the middle and southern part of the iVtlantic. 

 The foUowing species, as common on the shores of Great 

 Britain as of Sweden, viz: Achnanthes longipes, Actinoptychus 

 uudulatus, Surirella lata and fastuosa, Biddulphia pulchelhi, 

 Triceratium Favus and others are not found in any sample from 

 the arctic sea, except some of them in only one from Spets- 

 bergen, Kings Bay 160 fathoms deep. As I have not found 

 the species in any other sample 1 regard their occurrence as 

 doubtful and have consequently put a query before their 

 names in the following list. 



The diatoms found in the arctic samples examined by me, 

 are the following : 



