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



Table 50. 8. Extra II. 57° 43' N., 11° T E. 25. II. 1914. 



35 



■ta 



O. 



© 



Q 



©o 

 O. 



S £ 



£5 



O 



>> 

 -*a 



ja 



c? 



C 



Q 



Thalassiosira 

 Norden- 

 skiöldii 



Thalassiosira 

 gravida 



Thalassiosira 

 fallax 



'C ^ 

 © 03 

 -r) <D 



1 



Sceletonema 

 costatum 



.5 °ä 



P4 m 



03 



si 



03 



a 

 '3 5 



e3 



C .- 



■3 '3 



2 ° 

 1 £? 



Sm 

 



n 



^ 3 

 .3 



O 03 

 O 73 



a, to 



© 3 

 M T3 



c9 



g ä 



Li- 

 sa 



'2 Oj 



CD 



<s g 



© 3 

 « 



-» O 

 © *> 



03 C 



J3 O 

 O ° 



.3 



~3 'C 



T3 3 



n 



Thalassio- 



thrix nitz- 



schioides 



Diatoms 



total 

 numbers 







2,75 



27,56 



21,99 



20,500 



1,600 12,500 



4,900 



120,800 



500 



700 



100 



1,200 



800 



1,400 



15,600 



20,200 



207,940 



Ki 



2,92 



28,24 



22,54 



34,400 



3,600 3,600 



\ + 400 



4,100 



125,700 



2,200 



300 



400 



1,000 



500 



3,100 



15,900 



32,300 



241,800 



20 



3,37 



28,98 



23,08 21,200 



1,800 1,500 



+ 300\ 



3,100 



65,500 



1.400 



+ 1,200' 



200 



100 



600 



400 



1,900 



9,500 



17,200 



131,900 



30 



3,44 



30,21 



24,05 



15,100 

 + 300 



1,900 1,800 

 + 200\ + 400 



3,200 



146,100 



1,600 

 + 400' 



300 



200 



2,900 



100 



1,800 



+ 200 





37,900 



227,100 



stage, the springflow of Baltic water having already grown to a considerable extent and 

 mixed deeper through, in a manner to push away all the salter water of more than 30 %o- 

 It is for this reason most likely, that the tables do not give an adequate figure of the real 

 winter-maxima this year, much of the Sira-plankton being certainly already scattered by 

 the outflowing current that has eontribiited to the formation of such a mighty mixed layer. 

 Among the diatoms of the Northern Kattegat, Sceletonema is by far predominant, this 

 light little species thus seeming to thrive relatively well in the mix-water. Other characte- 

 ristic members of the Sira-formation are Biddulphia aurita, a marked wintcr-diatom, and 

 Thalassiothrix nitzschioides. The occurrenee of Guinardia and Paralia, somewhat evenly 

 distributed allthrough the water, bears evidence of its promiscuid origine. 



Table 51. S. Extra II. 57° 43' N., 11° 7' E., 25. II. 1914. 



J3 



a, 



© 



Tempera- 

 ture "C. 



O 



>, 



-*a 



'a 



0" 

 >. 



■4A 



"m 



d 



© 

 Q 



3 



d 



T3 







c 



a 



>> 



.2 



03 



© 







eridiniales 



total 

 numbers 



a 



'3 



•B 







w 



•S 



8 

 © 

 



J3 



03 

 l-l 



Protozoa 



total 

 numbers 



'k £ 



3 3 



ö w 



a 

 a % 



O Cl, 

 ■— ra 







CG 









EU 



s 







CQ 







2,75 



27,56 



21,99 



1,100 



100 



1,700 



2,500 



2,r,oo 



5,600 



400 



10 



2,92 



28,24 



22,54 



300 



100 



900 







500 



200 



20 



3,37 



28,98 



23,08 







600 





100 



1,000 



400 



30 



3,44 



30,21 



24,05 



100 



100 



200 







600 



2,600 



Gymnodinia have thus begun to develop in the surface-water, but not yet Ceratia. Al- 

 so the most common species of infusorians, such as Mesodinium rubrum and the Laboece, 

 are numerous enough here, but absent in other layers. 



In the 20 uppermost metres, the water is so strongly diluted by the Baltic Current, 

 that the diatomaceous plankton, otherwise much alike that of S. Extra II, is notably thinned 

 out. Only when the 30 °/oo limit is surpassed at a depth of 30 m, we meet again with 



The undermost numbers denote a small variety. 



