KONGL. SV. VET. AKADEMIENS 
Temora stylifera (s), 
Sagitta bipunctata (n), 
Globigerina bulloides (n), 
Codonella lagenula (s), 
Cyttarocylis acuminata (s), 
C. cassis (s), 
C. ganymedes (s), 
C. Treforti (s), 
Dictyocysta elegans (e n), 
D. mitra (s), 
Tintinnus Fraknot (s). 
HANDLINGAR. 
BAND 32. wo 3. 5 
Peridinium oblongum' (n), 
Chetoceros furca (s), 
C. Lorenziana (s), 
C. volans (n), 
Corethron hystria (e n), 
Coscinodiscus sol (e), 
Dactyliosolen antarcticus (e n), 
Hemidiscus cuneiformis, 
Rhizosolenia alata (n), 
R. gracillima (n), 
R. styliformis (n). 
The derived stylitypes of the North Sea, the didymus- and tripos-plankton, are 
characterized as follows. 
A. Didymus-plankton (Sign Ni). 
This plankton-type rules in the summer and 
autumn along the southern coasts of the German Ocean above the 50 metre-plateau of 
the bottom. 
The temperature varies between 8° and 17° and the salinity is about 32 or 33 p.m. 
The organisms are numerous and the diatoms constitute an important part of them. 
Among the animals many are common to didymus- and triposplankton and their names 
are in the following lists enclosed in parenthesis. 
Animals. 
(Acartia Clausit), 
(Centropages hamatus), 
(C. typicus), 
Coryceus anglicus, 
Isias clavipes, 
c Labidocera Wollastonii, 
(Oithona similis), 
(Paracalanus parvus), 
Podon polyphemoides, 
(Sagitta bipunctata), 
Oikopleura dioica, 
Noctiluca miliaris, 
Tintinnopsis campanula. 
As the more common species we note: 
Plants. 
Bacteriastrum varians, 
Biddulphia mobilensis, 
Cerataulina Bergonit, 
Chetoceros curvisetus, 
C. danicus, 
C. didymus, 
C. Schiittii, 
C. Weissflogit, 
Ditylum Brightwelli, 
Eucampia zodiacus, 
Guinardia flaccida, 
Rhizosolenia Shrubsoltt, 
R. Stolterfothat, 
Streptotheca tamesis. 
B. Triposplankton (Sign 7p) 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. 
cheeto-plankton. 
1 Perid. divergens v. oblonga AURIV. 
In the spring it is replaced by water with 
