KOXGL. SV. VET. AKADEMIENS HAXDLISGAH. BAND 32. N:0 8. 5 



Among the species inentioned above, Halospkcera is not equallv distributed över the 

 ■\vhole cha;to area. It could be traced froin the south west of Norway to Newcastle and 

 as far to the north as beyond the 63rd degree of latitude and 0° long.; also from the 

 soQth of Norway to Skagen and into Skagerak. 



2. The North Sea in June 1898. 



The chieto-plankton of the spring has almost completelj disappeared, some few 

 remnants lingering west of the Daaish Peninsula (at 56° N.) and west of Norway (61'X. 

 2° 30' E.). Its place is now occupied by tripos-plankton, which is the ruling type at this 

 time of the year. It is more richly represented in the eastern than in the western parts 

 of the area. 



To the east of the British coast the tripos-plankton is mixed ^nth northern neritic 

 forms, sucb as Ceratium tripos v. longipes, and at the west of the Danish Peninsula and 

 north of the German coast with Peridinium depressum. 



The southern part of the Xorth Sea contains, north of the Continental coast, southern 

 neritic plankton, mixed with styli-plankton. 



The hydrographical map for June 1898 by Ek3Iän and Pettersson shows in the 

 north between Norway and Scotland a tongue of 35 p. m. water, temp. 9" to 10'. No 

 samples of plankton from this area have been examined bv me. One sample from 

 61° 50' N. 2' 30' E., which mav be assumed to be from that kind of Avater. contained tripos- 

 plankton, but not abundantly. 



The bulk of tripos-plankton in mv samples had coiiie from the northern or eastern 

 part of the region coloured as containing 34 p. m. water. 



The hydrographical map in its south western corner shows an. area of 35 p. m. 

 water, indicating that a flow of Atlantic water enters into the North Sea from the south. 

 This fact accounts for the considerable development of the southern neritic plankton above 

 the 50 metre plateau. 



Species wMeli seem to come into the ^ortli Sea roTuid the nortli of Scotland. As 



stated above there are among the plankton, some northern species east of the Scotch coast 

 to Newcastle, such as Ceratium longipes. But, on the other hand, there are also in the 

 western region of the North Sea some southern species. I name the following: 



Northern forms Southern forms 



Calanus jinmarehiciis, Åcartia Clausii, 



Evadne JS^ordmannii, Labidocera WoUa^tonii, 



Cyttaroc.ylis gigantea. Evadne spinifera, 



Ceratium macroceros, 

 Lauderia annulata. 

 Peridiniutii divergens. 



