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



17 



At this easternmost station, the plankton is very similar to that of S. Extra II. 

 The heaping of Paralia in the middle layers may be the effect of a steady increase of den- 

 sity upon the sinking råte. From — 80 m, the distribution of Navieuloid forms, such 

 as Navicula distans and N. Schmidtii v. shigerakiensis n. var., several species of Pleuro- 

 sigma and small Xitzschice (cfr. part II of this paper, dealing with the biology of the or- 

 ganisms) is so regular, that an average number of frequency may well be sought for the 

 whole column — 80 m; it amounts to 244 ind. per 1. Such immigrants from warmer parts 

 of the North Sea as Biddulphia sinensis and Rhizosolenia fragilissima are rare or missing. 



Table 17. S. Skag 0. 57° 41' N., 11° 24' E. 5. XI. 1912. 



J2 



O. 

 8 



Q 



gö 



tio 



o. 



S £ 



• 3 



>> 



"3 



t» 



o" 



>> 



•** 



'äa 



C 

 <0 



d 



Disteplianus 

 speculum 



ij 



3 T3 

 .£ CD 



<S £ 

 C 



c 



3 c3 



2.2 



m 



Ceratium 

 fusus 



Ceratium 

 longipos 



Ceratium 

 lineatum 



Ceratium 

 macroceras 



£ CO 



2 o 



'-« c 



fe-> 



o 



"3 



O t. 



•Bl 



53 2 



<D 



Prorocent- 

 rum micans 



Peridiniales 



total 



numbers 







7,76 



33,06 



25,81 



20 





80 











120 



200 



20 



260 



10 



8,40 



33,26 



25,91 



80 





40 



80 



40 







140 



300 





400 



20 



9,10 



33,57 



20,02 



10 



30 





30 







40 



10 



110 



20 



300 



30 



9,19 



33,60 



26,04 



100 







20 



20 



20 



80 



40 



180 



20 



220 



40 



9,27 



33,73 



26,11 



10 



10 







10 



20 



30 



20 



90 





190 



50 



9,23 



33,78 



26,18 



10 







10 



10 





50 





70 



10 



200 



60 



8,02 



34,11 



26,53 























100 



80 



8,10 



34,52 



26,92 























110 



98 



7,74 



34,72 



27,13 























70 



The Ceratia being decided light-organisms of the uppermost strata, their distribu- 

 tion marks quite distinctly the existence of a lower limit of the vertical currents at S. 

 Skag. 0, which falls between 50 and 60 m. As seen in Table 17, the water at this depth 

 just becomes somewhat colder and salter than in the overlayering, for at least 40 m very 

 uniform part of the column. 



Table 18. S. Skag. 5. 57° 42' N., 9° 61' E. 6. XI. 1912. 



o. 



v 



Q 



Tempera- 

 turs c C. 



g 



ä 



"3 



c» 



h 

 .-a 



tr. 

 C 

 cs 



cd cä 

 S o 



fe s 



Hyalodiscus 

 stelliger 



Coscino- 

 discus spp. 



Guinardia 

 flaccida 



Rhizosolenia 

 semispina 



.2 00 



c 'c 



!° 



o — 

 S TT 

 •— ^i 



■° S 



Thalassio- 



thrix nitz- 



schioides 



Tlialassio- 



thrix 

 Frauenfeldii 



Biddulpliia 

 sinensis 



Navieuloid 

 diatoms 



Diatoms 

 total 



numbers 







7,93 



33,24 



25,93 



710 



30 



30 



60 





30 



100 



30 



30 



630 



2,150 



10 



9,04 



33,06 



26,09 



1,960 



90 



20 



20 





15 



100 



40 



90 



700 



3,215 



20 



9,46 



33,80 



26,12 



1,920 



110 



10 



30 





5 



60 



80 



70 



710 



3,155 



30 



9,95 



34,11 



26,30 



1,370 



40 



25 



20 





10 



30 



110 



20 



210 



1,985 



40 



10,17 



34.18 



26,30 



1,970 



30 



65 





5 



5 



80 



100 



23 



400 



2,880 



50 



i 



10,20 



34,18 



20,30 



4,950 



80 









20 



00 



160 



20 



(+10) 



250 



5,060 



This station presents the same general features as S. Extra II, the meridional 

 character being only more accentuated. There is a real Styli-plankton regularly mixed 



K. Sv. Vet. Akad. Handl. Band 57. N:o 7 3 



