KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BÄND 57. N:0 7. 



Table 1. 8. Extra II. 57° 43 r N., 11° 7' E. 16. VIII. 1912. 





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08 



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3 



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- £ 



■5 0! .2 



I a 



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73 a 



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2 05 



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'c 

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04 



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Ils! 



.2 - 3 ■ 



C c 







i 16,10 



31,69 



23,21 











120 



20 



180 



380 



3,000 



160 



340 



10 



16,43 



32,52 



23,38 







20 



20 





40 



250 



1,660 



2,780 



160 



280 



20 



16,07 



32,66 



23,81 



200 



400 



140 



' 



140 



180 



1 ,320 



520 



1 ,060 



100 



100 



30 



16,(>o 



32,74 



23,90 





660 



40 







140 



1,030 



240 



600 



130 



130 



3S 



16,5 4 



32,77 



23,95 



120 



160 









40 



360 



20 



80 



40 



40 



teristic of the now ruling Tripos-plankton. Its frequency is, however, smaller than might 

 perhaps be expected, or only 140 ind. per 1. In the deeper layers, from about 15 m to 

 the bottom, Thalassosira gravida is the most common species, reaching a maximum of 

 660 ind. per 1. The total amount of diatoms is 1 argest at 20 m, counting 1320 ind. per 1, 

 from where it decreases slowly towards the bottom, more abruptly towards the surface, 

 Though the water is rather uniform, showing the high temperature of c. 16,s° all through. 

 and a salinity varying only between 31,7 %o an( l 32,8 %o» the diatomous flora is thus an- 

 other in the upper than in the lower layers, no doubt in consequence of the very different 

 floating-power of the delicate Rhizosolenia on one side, and such big and solid forms as 

 Thalassiosira and Paralia on the other. 



In table 1, there is a column reserved for Navieuloid diatoms and singly living 

 Nitzschiae, that begin to play a role in the summer-plankton and increase in importance 

 låter in autumn, as will be shown by the November-tables. Some spread exponents of the 

 southern-neritic (Xm)type of Cleve, in the first place Bacteriastrum that is rarely found 

 in the Skager Rak, demonstrate the presence of southern North-Sea-water, the so-called 

 southern bank-water of the Swedish hydrographs. The presence of Thalassiosira gravida 

 at this station is remarkable, as we do not find it anywhere in the Skager Rak proper, if 

 not quite singly. 





Table 



! 2. 



S. Extra II. 



57° 



43' N 



., H° 



7 E 



. 16 



. VITT. 



1912. 



43 



B. 



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£2 £ 

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3 

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*- 8 



.S -S- 2 



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16,10 



31,69 



23,21 







00 



40 



200 





40 



380 



1,300' 

 (+ 120) 



580 



2,880 

 (+ 120) 



10 



16,43 



32,12 



23,38 







40 



120 



1,400 





80 



1,660 



380 

 (+ 120) 



260 



2,660 

 (+ 120) 



20 



16,67 



32,66 



23,81 







20 



40 



440 





20 



520 



340 



(+ 80) 





980 



(+ 80) 



30 



16,60 



32,74 



23,90 







20 



220 







240 



180 



(+ 80) 





520 



(+ 80) 



38 



16,54 



32,77 



23,95 











20 







20 







40 



1 The numbers enclosetl refer to empty shells. 



