607 



along with ils poor Discoplankton , in which some Peridiniaceae 

 occur in solitary examples. 



1902, Table IX. In the beginning of March the oceanic Chæto- 

 planktoD occurs, bul in the middle of the raonth it is covered by 

 Siraplankton with Thalassiosira gravida, Nordenskioldii, and Biddul- 

 phia aurita; at the end of March tliis again gives plaee to Contorto- 

 plankton with Chaet. debile; this disappears in Maj f and a plankton 

 consisting of Chaetoceras constrictum, C. decipiens, Coscinodiscus con- 

 cinnus, Rhizosolenia obtusa and Phaeocystis prédominates ; this asso- 

 ciation appears to he closely related lo the one which occurred in 

 May — June 1898, and must doubtlcss be regarded as Chætoplanklon 

 (oceanic) which by coming in contacl with the coast became over- 

 grown with neritic forms. In the middle of June Phaeocystis pre- 

 dominated, and the diatoms which occurred were almost all dead. 



Unfortnnately, there is now a gap in the gatherings until the 

 beginning of August, when a rich Solenia|)lankton as mel with, in 

 which, strangely enough Thalassiosira gravida and Nordenskioldii 

 are also common; otherwise it is characterized by the presence of 

 Rhizosolenia faeroensis and Thalassiosira bioculata, the former dis- 

 appears in August, while the latter hecomes more and more domi- 

 nant towards the end of September when the gatherings ceased. — 



If we sum up the proceeds of the development of the plankton 

 in these two years, we find that, as in the more oceanic samples, 

 the associations make their appearance in the same succession and 

 at about the same time: — in the winter we have Disco- and 

 Sphæraplankton; the first spring-plankton is Siraplankton, then comes 

 Contortoplankton ; in early summer the resemblance between the 

 two years is less; in May Phaeocystis and Rhiz. obtusa are met 

 with, and, moreover, Chæto- (and Nitzschia-) planklon occur more 

 or less indistinctly, but some species, e. g. Ch. constrictum and 

 Leptocylindrus are observed abundantly in the one year, but are 

 almost absent in the other. Soleniaplankton occurs late in sum- 

 mer, and in 1902 several rare species predominate in it. This 

 enormous development of single species is peculiar to the coastal 

 conditions, and, also, this development does not re-occur every year 

 in the case of all the species. The waters of the ocean, so to speak, 

 rouses the reposing coast-forms, but this recall to activity does not 

 take place with absolute regularitv; il appears to be dependant on 

 circumstances which are as vel unknown; we mav eompare this 

 phenomenon with the well-known faet in the case of the higher 



