the young Calanus finmarchicus of the second, that is the summer, generation. 



Species -wise, the composition of the plankton sample that was taken from the central re- 

 gions of the Norwegian Sea on August 3, 1953 (the 0-10 m. layer) appeared as follows: 



Ceratium longipes 



C. fusus 



C. tripos 



C. macroceros 



Parafavella gigantea 



Calanus finmarchicus nauplii 



-I-II copepod stages 



Oithona similis 



Onceae borealis 



Evadne nordmanl 



Fritillaria borealis 



Berfle cucumis juv 



Gastropoda juv 



Lamellebranchia juv 



Limacina retroversa juv 



Single specimens of these species of plankton were encountered 

 in the sample . 



fair number (the second, the summer generation) . 

 few 



many 

 singly 



20' 15' 10 y 0' y to- ir 20' w jo- w 



Figure 4. Times of the onset of the biological spring in the various regions of the Norwe- 

 gian Sea (the Roman numerals indicate the months) . 



113 



