KONGL. SV. VET. AKADKMIENS HANDLINGAR. 



BAND 



32. 



n:o 



Temora stylifera (.s), 

 Sagitta bipunctata (n), 

 Glohigerina bulloides (n), 

 Codonella lagenula («), 

 Cyttarocylis acuminata (s), 

 C. cassis (s), 

 C. ganymedes (s), 



C. Treforti (s), 

 Dictyocysta elegans {e ??), 



D. mitra (.s), 

 Tintinnus Fraknoi (s). 



Peridinium oblongum ' (n), 

 CJicetoceros fur ca (s), 

 C. Lorenziana (s), 

 C. volans (n), 

 Corethron hystrix {e n), 

 Coscinodiscus sol {e), 

 Dactyliosolen antarcticus (e n), 

 Hemidiscus cuneiformis, 

 Rhizosolenia a lata (n), 

 R. gracillima (n), 

 B. stylifor)vis (n). 



The derived stylitypes of thc North Sea, the didymus- and tripos-plankt07i, are 

 characterized as follows. 



A. Didymus-plaiikton (Sign Hm). This plankton-type rules in the suinmer and 

 autumn along the southern coasts of the German Ocean above the 50 metre-plateau of 

 the bottom. 



The ternperature varies between 8° and 17° and the salinity is about 32 or 33 p. m. 



The organisms are numerous and the diatoms constitnte an important part of theni. 

 Among the animals niany are common to didymus- and triposplankton and their names 

 are in the foUowing lists enclosed in parenthesis. As the more common species we note: 



Animals. 

 (Acartia Clausii), 

 {Centropages hamatus), 

 {C. tyjjicus), 

 Corycasus anglicus, 

 Isias clavipes, 

 Labidocera Wollastonii, 

 {Olthona similis), 

 {Paracalanus parvus), 

 Podon polyphemoides, 

 (Sagitta bipunctata), 

 Oikopleura dioica, 

 Noctiluca miliaris, 

 Tintinnopsis campanida. 



Plants. 

 Bacteriastrum varians, 

 Biddidphia mobilensis, 

 Cerataulina Bergonii, 

 Chcetoceros curvisetus, 

 C. danicus, 

 C. didymus, 

 C. Schiittii, 

 C. Weissjiogii, 

 Ditylum Brightwellii, 

 Eucampia zodiaciis, 

 Guinardia flaccida, 

 Rhizosolenia Shrubsolii, 

 R. Stolterfothii, 

 Streptotheca tamesis. 



B. Triposplankton (Sign Ip) rules in the summer and autumn in the northern 

 part of the North Sea above the 100 metre-plateau of the bottom and extends from 

 Scotland to Scandinavia as far as Finmarken. In the spring it is replaced by water with 

 chjeto-plankton. 



^ JPerid. divergens v. oblonga AURIV, 



