It is a Avellknown fact that the open sea is sometimes co- 

 loured for considcrable distances by a great number of small mi- 

 croscopical orp^aiiisms, . swarming close to the surface. Seafarino- 

 people oall it "sairdmt sea'', biit verv few scientific researches on 

 the organisms, living in such a manner have been yet published. 

 The only complete examination, of which I am cognizant, is 

 by Gkunow *), who enumerates 13 difFerent forms of diatoms, 

 ■collected near the Xicobarian Island Tilanschang and found 

 there on the surface of the sea. 



I was just engaged in examining a larger number of 

 samples of diatoms, collected on the open sea during the last 

 two Swedish arctic expeditions to Greenland and of which I 

 intend shortly to give a complete account, when I received 

 by the favour of Prof. LovÉxN a sample of diatoms, collected 

 by Captain Knoll on the surface of the sea of Java Lat. 4" 20' 

 ■S. Long. 105" 22' O. The mäss, preserved in alcohol, consisted 

 almost entirely of diatoms, but it contained also some animals 

 such as smaller crustaceans, radiolaria and especially a Peridi- 

 nium, which animal also occurs under similar circumstances the 

 northern Atlantic. 



A very complete investigation of this diatoniaceous mäss 

 yelded about 50 different species of diatoms, the most common 

 among them being represented by ChaHoceros, Bacteriastriim, 

 Ehizosolenia and Coscinodiscus. The oceanic forms from the- 

 northern Atlantic and from Davis Strait, Avhich I have exa- 

 mined, bclong also for the most part to the genera Clia^toceros 

 and Rhizosolenia, but Bacteriastrum is entirely absent and Co- 

 scinodiscus is somewhet rare. It was a \Qxy interesting fact to 

 find that some of the species, living in the northern Atlantic 



*) Verhandlungen der k. k. zoolog, bot. Ges. in Wien 1863. pag. 140. 



