KONGL. SV. VET. AKADEMIENS IIANDLINGA7?. 



BAND 



35. 



n:0 



B. The Skagerak. The only samples examined were from Måseskär and Väderö- 

 boda. To judge from these samples the formerly prevailing arctic and boreal species had 

 disappeared or died out. Still Ceratiuin lonnipes and Coscinodiscus concinnus are abundant 

 and more common than formerly. On the other hand a number of southern forms com- 

 mence to develop, for instance Acartia Clausii, Oithona similis, Evadne Nordmani, Rhizo- 

 solenia gracillima. 



June 1900. 



A. The North Sea. The only samples received that month were 7 collections taken 

 by a fishing-boat on the 18th to 30th of June near the Shetland Islands, at 60° 20'— 60°40'N. 

 0° 17'E— 2°45' W., in water of the salinity 35,29 to 35,45 and the temperature 9,8 to 13,2. 



The samples contained the foUowing species: ^ 



Cleodora pyramidata c, 

 Acartia Clausii r, 

 Calanus finmarchicus c, 

 Metridia lucens +, 

 Oithona jylumifera r, 

 O. similis +, 

 Oncwa minuta rr, 

 Pseudocalanus elongatus +, 

 Ecadiie ^^orchyTiDii +, 

 Amphorella Norvegica rr, 

 Cyiiarocylis denticulata c, 

 Acantiwmetron cateroatum 

 Cei'atium biicephalum r, 

 C. furca c, 

 C. fasus r, 

 C. longipes c, 

 C. macroceros rr, 

 t '. fripos + , 

 Dinophysis acuta r, 



+ , 



Diplopsalis lenticula r, 



Peridinium depressum +, 



P ovatum + , 



P. pellucidum r, 



Dinobryum pellucidum r, 



Chaetoceros boreal/s r, 



C. decipiens r, 



C. Loremianus r, 



C. peruvianiis r, 



Coscinodiscus oculus iridis r, 



Dactyliosolen antarvticus rr, 



Guinardia ftacuida r, 



Lauderia annuluia r, 



Rhizosolenia alata r, 



R. (jracillima c, 



R. semispina + , 



R. Shrubsolei r, 



R. sti/liforinis c, 



Thalassiosira Nordenskiöldii +. 



This list shows that the plankton was a mixture of styli-plankton and a number 

 of boreal species. Especially interesting is the occurrence of Thalassiosira Nordenskiöldii 

 at that time of the year near the Shetlands. Cleodora pri/ramidata is also of interest. 

 According to Boas '" and Munthe '^ the distribution of this pteropod is in the north of 

 a line between Buenos Ayres and the Cape of Good Hope to about 50° N., besides, accor- 

 ding to Boas, from the mouth of Davis' Strait to the Shetlands. This species thus belongs 

 to the desmo-plankton. The occurrence of the antarctic species Dactyliosolen antarcticus 

 is also remarkable. 



' Boreal or arctic forms marked by larger types. 



- Acta Havn. (6) IV n. 1 p. 69 1886 



3 Bihang till K. Sv. Vet. Ak. Handl. Vol. XIII Part. IV n:r 2 p. 17. 



K. Sv. Vet Akad. Handl. Band 35. N:o 7. 



