KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 32. N:0 8. 



31 



3. From April to October: Phceocystis Pouchetii. 



4. From May to November, December: Eucampia zodiacus, Guinardia flaccida, 

 Rhizosolenia Shruhsolei and E. Stolterfothii. 



5. In June: Choetoceros Villei, Stephanopyxis turgida. 



6. From June to November, December: Centropages hamatus, Tintinnopsis be- 

 roidea var. acuminata, Chcetoceros densus, Lauderia annulata, Rhizosolenia setigera, R. 

 styliformis. 



7. From July, August: Oikople.ura dioica, Proto pedata, Paracalanus parvus, 

 Tintinnopsis campanida, T. ventricosa, Noctiluca niiliaris, Bacteriastrum varians, Chce- 

 toceros anastomosans, C. coronatus, C. didymus, C. curvisetus, Rhizosolenia deli- 

 catula. 



8. From September: Ptychocylis Clapnredii, P. Ehrenhergii. 



9. From October, November: Acartia hifilosa, Euterpe acutifrons, Bellerochea mal- 

 lens, Choitoceros danicus, C. Schiittii, Lithodesmium undulatum, Rhizosolenia calcar avis, 

 R. robusta. 



All these forms are, with the exception of Phaiocystis Pouchetii, of southern habitat. 



B. 



Forms tliat, as a riile, are conflned to the space above the 100 metre plateau. 



Spring-forms, or such as occur in March: 



Southern forms: 



Microsetella atlantica, 

 Oithona similis, 

 Äcanthometron quadrifolium, 

 Halosphcera viridis. 



Northern forms: 



Metridia hibernica, 

 Ceratium longipes, 

 Chcetoceros horealis, 

 v. Brightwellii. 



2. Summer-forms, or such as occur in June, July, August: 

 Southern : 



Evadne spinifera, 

 Ceratium tripos, 

 C. macroceros. 



3. Autumn-forms, or such as occur in October: 



Centropages typicus (southern). 



4. Winter-forms, or such as occur in November: 



Southern : 



{Äcanthometron quadrifolium), 

 {Halosphcera viridis), 

 Ceratium tripos v. bucephala. 



Northern: 



Evadne Nordmannii, 

 Acartia longiremis, 

 {Metridia hibernica). 



Northern: 



( Calanus jinmarchicus), 

 Limacina balea, 

 Dinophysis acuta. 



The parentheses denote that the enclosed species also occur in the spring. 



