PELAGIC PLANT LIFE 357 



The plankton of the cold water on the Newfoundland Bank The Nc 

 was very poor in species, Ceratijim arcticum and Peridinmm g^^k^^ 



parallelum being the commonest forms. There were, besides, (Stations 70 



9, 3( 



loth July.) 



a few diatoms, such as Chcetoceras atlanticum, C. criophihim, 79, 30th June 



and Rhizosolenia seynispina, all well-known species in the 

 Norwegian Sea. In the harbour of St. John's, on the other 

 hand, we found the plankton quite abundant, consisting of 

 northern forms, both neritic and oceanic : the species of Chce- 

 toce7'as {decipiens, debile) predominated. 



to our 



ir northern section across the Atlantic contributed largely 

 knowledge of the distribution of species, since it showed 



Atlantic 

 section. 

 (Stations 8i- 

 92, I2th-24th 



July.) 



Fig. 2^().—Chmtoceras perpusillum (^f^). 



US that a great many tropical forms are still to be found in lat. 

 45-50^ N. These particular waters had been very little studied 

 previously, and it was extremely interesting to follow all this 

 Atlantic flora on its passive journey northwards. On the whole, 

 its character remains unchanged, though of course the number 

 of species becomes considerably reduced. During the first half 

 of the section, on the western side of the mid-Atlantic ridge, 

 there were a few small degenerate neritic diatoms belonging to 

 the species which occur in the Atlantic water-masses south of 

 Iceland : namely Chcutoceras schiittii, C. laciniosimi, and others. 

 It seems unquestionable that they are derived from the American 

 coast, and follow the current as far as Iceland. At Station 85 I 

 also came across a remarkable little ChcEtoceras, that Cleve found 

 in 1897 ^^ ^^ Skagerrack and named ChcBtoceras perpusillum 



