64 UJOKT'S HYDKOGRAPIIIC-BIOLO(rICAL STUDIP^S 



up in the Cattegat, and formed but a shallow surface layer in Christiania 

 fjord. On November 12th the surface temperature was 4*3°. The 

 tow-nets brought up plankton consisting almost exclusively of vegetable 

 organisms, viz., a few Cilioflagellata and an abundance of Diatomaceae, 

 especially Chcctoceros curvisetus and a species of lihizosolenia. The 

 abundance of Diatomaceie within a short distance from the surface 

 (0 to 10 metres) was clearly correlated with the shallowness of the 

 Baltic layer, whereas in 1893, owing to the great thickness of the Baltic 

 layer, these organisms were only plentiful at a considerable depth. 



On the west coast, in the autumn of 1893, Baltic water was only 

 found inside the fjords. In Hardanger fjord, on November 22nd, 

 (temperature 7° to 8° C.) the tow-net brought up only a few Copepods 

 and Evadne, but a mixed collection of numerous Cilioflagellates {G. 

 tripos) and Diatomacece {Chcetoceros cUdymus and horealis). In November, 

 1894, on the other hand, the Baltic current was very extensive, and the 

 surface collections (November 26th, temperature 7'5°) showed accord- 

 ingly a sparsity of Diatoms and an abundance of Cilioflagellates (C. 

 tripos), together with numbers of Oithonella pygmcca (Copepod) and 

 Evadne Nordmanni. 



In winter the surface waters were mostly bank or North Sea waters, 

 and no collection of plankton were taken in Baltic waters. 



In spring (April 16th, 1894) on the west coast the Baltic currents, 

 having a salinity of 30 per thousand and a temperature of 6° C, contained 

 principally Cilioflagellates (C. tripos), Halosphccra viridis, Evadne 

 Nordmanni (with young), and young Calanids. 



2. The Bank Waters. — Attention has been previously drawn to the 

 fact that bank water bathed the whole west coast of Norway in the 

 autumn of 1893. In the Norwegian channel off Ekersund on November 

 15th the salinity of the surface water was 33*38 per thousand, and the 

 temperature approximately 9^ C. The plankton was abundant, and con- 

 consisted principally of the Copepod Pscudocalanus elongatus, Evadne, 

 Sagitta, Radiolaria, Cilioflagellates (0. tripos), and Diatomacea3 {Chcctoceros 

 horealis and curvisetus). 



Off EspevcXT, on December 15th, 1894, on the other hand, the salinity 

 of the surface bank water was somewhat lower (32-98 per thousand), and 

 the temperature 7°. Nevertheless, the plankton was very abundant, and 

 consisted principally of Cilioflagellata {C. tripos), together with numbers 

 of the Copepod Oithonella pygmma and a few Pseudocalanus elongatus. 

 The absence of Diatomacerc will be noticed. 



In the winter of 1894, on the west coast, the surface bank water had 

 a high salinity, and on February 28th was practically North Sea water 

 (salinity 33'92 per thousand, temperature 5°). It contained an abundant 

 plankton, consisting principally of the Copepods Cynthilia Clausi, 



