16 



ASTRID CLEVE-EULER, QUANTITATIVE PLANKTON RESEARCHES IN THE SKAGER RAK. 



downwards, being obviously at the end of its autumnal maximum. The single living 

 Naviculoid forms and Nitzschice, as well as the mostly free cells of the similarly formed 

 Thalassiothrix nitzschi oides and litoral forms on the whole now have their best time, the 

 feeble floating-power being supplied in autumn by lifting eurrents. Still, the density 

 seems to be insufficient to hold Paralia staying long at the surfaee. Together with the 

 autumn-flowering algae, a real winter-flora is already there, Thalassiöthrix nitzschioides 

 first and foremost, then, though still in decent numbers, the common species of Thalassio- 

 sira. Evidently, they are only waiting for a sufficient fall of temperature, and probably, 

 for a returning light to begiii a more intense development towards the winter maximum. 



Table 15. S. Extra II. 57° 43' N., 11 T E. 6. XI. 1911. 





5Ö 



O 



o 



o* 



t/J 



fl - 



fl S 



s 



£.2 



s 



£ 



fl CO 



s s 



cm 



fl as 



£ 



a 



CO 



CO 



-i; co 



-C 



0. 

 CD 



Q 



<1> O 



O. 



S £ 



CD 3 



'a 



>> 



.-s 



a 



fl 



* 3 



s-o 



« c 



3 fl 



« 2 



cd 



.2 3 



2 s 



CD "*" 



.2 a 



g c 



CD c 



3 3 



3* 



SS 



■2 8 

 • 2 



.2 g 



t- b 



CD *- 



*• CD 



•si 



C3 3 



53. i 

 S£ 



2F 







H *> 



03 



Q 



g. 



u .s 



O 



O 



o- 



o - 



°S 



O 



CD 



Äg 



0- 







7,09 



32,52 



25,39 



120 



40 



250 



80 



70 



170 



70 



100 



810 



150 



1,150 



10 



7,75 



32,63 



25,48 



90 



80 



260 



60 



20 



70 



50 



90 



650 



130 



970 



20 



8,59 



33,12 



25,73 



60 



5<> 



180 



30 





20 



20 



150 



470 



100 



790 



30 



8,62 



— 



- 



60 



60 



50 



50 





60 



40 



40 



3<>o 



10 



610 



38 



8,96 



33,39 



25,88 



50 



10 



20 



30 





10 



40 



40 



160 



10 



620 



The above figures show, by the little varying numbers of Peridiniales through the 

 vertical columns, that the Ceratia are at the end of their maximum-season. Only C. li- 

 neatum, that is a youth-stage of C. tripos, is still aceumulated at the surfaee, sinking less 

 rapidly then the rest. Also the small Prorocentrum, so numerous in the uppermost layer 

 in August, is getting diffused and has gone to rest. Other peridinians are scarce. 



Table 16. S. Skag. 0. 57° 41' N., 11° 24' E. 6. XI. 1912. 



o. 



CD 



Q 



Tempera- 

 ture 'C. 



§ 



fl 



"a 

 t» 



>> 



CO 



C 



CD 



Q 



■— ** 

 2 S 



fl "q 



Guinardia 

 flaccida 



Thalassiosira 

 gravida 



Thalassiosira 

 Norden- 

 skiöldii 



Hyalodiscus 

 stelliger 



Rhizosolenia 

 alata 



Rhizosolenia 

 fragihssima 



Thalassio- 

 thrix nitz- 

 schioides 



Biddulphia 



sinensis 



Naviculoid 

 forms and 

 Nitzschiae 



Diatoms 



total 

 numbers 







7,76 



33,06 



25,81 



460 









20 







180 





160 



1,300 



10 



8,40 



33,26 



25,91 



600 



120 



40 



60 









4(1 





380 



4,160' 



20 



9,10 



33,57 



26,02 



2,340 





10 





50 







80 





350 



3,215 



30 



9,19 



33,r,o 



26,04 



1,140 







•JO 









100 





200 



2,260 



40 



9,27 



33,73 



26,11 



2,990 





20 



40 



50 



lo 





120 



10 



280 



3,055 



50 



9,23 



33,78 



26,18 



2,170 















60 



20 



220 



2,630 



60 



8,02 



34,11 



26,53 



930 





10 





10 







50 





230 



1,360 



80 



8,10 



34,52 



26,92 



790 









10 







130 



10 



130 



1,110 



98 



7,74 



34,72 



27,13 



650 









10 







10 



5 



50 



775 



1 The high number is due to an isolated occurring of Sceletonema in 2,200 ind. per 1. 



