14 



1'. T. CLEVE, PLANKTON-KESEARCHES IN 1897. 



As transported by the scottish curreiit I consider the following: 



Pseudocalanus elongatus, ~^/x, (still uncertain whether partly iiidigenous in the Ska- 

 gcrak or arrived with the Scottish or Baltic currents.) 



Flectophora arachnoides, ^^/x- 



Halosphcera viridis, ^^/x. 



Coscinodiscus concinnus, ^^/x. 



Ceratium tripos var. biccephala, **/xi in the Skagera,k. 



Lauderia anmdata, */xii. 



Among northern forms, belonging the northern neritic plankton or to the arctic 

 sira-plankton , I note the following: 



A. Found from the 9*^' or L9^'' of October: 



Cyttarocylis denticulata. 

 Dinophysis acuta. 

 Gonyaulax spiinifera. 

 Chcetoceros horealis. 

 C- constrictus. 

 C. contortus. 

 C. debilis. 



Chcetoceros diadema. 

 C. laciniosus. 



Coscinodiscus oculus mridis. 

 Skeletonema costatum. 

 Tkalassiosira gelatinosa. 

 Thalassiotlirix longisshna. 



B. Found from November : 

 Thalassiothriai Frauenfeldii, ^/xi . 

 Biddulphia aurita, ^®/xi- 



C. Found fr st in December: 

 Ptyehoeyclis acuta. 



P. obtusa. 

 Tintinnus secatus. 



To sinn iip the abovc statenients I forniulate tlie plankton in the following nianner: 

 Pi^ Period */i to ""u Tp. T. 



11'^ 



IVth 



yth 



^'In to Viv 



«/iv to '^Vv 



A. ^^/vi to the beginiiing of August 



B. From August to ''/x .... 



19/ t„ 23/ 



/x 10 /xii 



(Tp. T.) Si. C. Ns. 



(C. Ns.) Tp. Nm. 



Tp. Nm. 



Tp. Nm. S. 



(Tp. Nm. S.) Ne. Nh. Ns. T. 



Of tlic above s}'mbols Tp denotes tripos-plankton, T tricho-plankton, Si sira- 

 plankton, C cha.'to-plankton, S styli-plankton, Ne and Nh plankton with Coscinodiscus 

 concinnus and Halosphasra, Nm southern and Ns northern coast-plankton. 



There is thus on the ivhole the same succession as has been found during the two 

 preceding years. 



