OF THE NORWEGIAN FISHERIES : A REVIEW. 65 



Calanus finmarchicus, and Metridia lucens, together with a large number 

 of the Diatom Coscinodiscm. On March 20th, 1894, the salinity was 

 lower (33"51 per thousand, temperature 4-9°), and the plankton consisted 

 chiefly of Pseudocalanus clongatus, Paraccdanus parvus, Sagitta, and the 

 Diatoms Cosciniodiscus and Chcctoceros decipiens. 



In the winter of 1895, on the west coast, the salinity of the surface 

 water inshore was lower than in 1894. Thus on February 9th west of 

 Utsire it was 33'67 per thousand, and the temperature 4°. Further inshore 

 the salinity was only 32 per thousand, and the temperature 2°. The 

 plankton was correspondingly sparse, consisting principally of Cilio- 

 flagellates aud a few Copepods. On the 25th of the same month 

 west of Utsire the salinity* at the surface was 33*14 per thousand, and 

 the temperature 4*3°. Except for a number of fish eggs, the plankton 

 consisted principally of Diatoms (especially Chcetoceros decipiens) and 

 Halosphcera viridis. Further north, off Vigteu, on February 21st 

 (salinity 33'34 per thousand, temperature 5"1°), the chief contents of the 

 tow-net were Calanus finmarchicus and Metridia lucens, the plankton 

 consisting principally of Crustacea, though not in quantity. 



3. North Sea Water. — In the winter of 1894 the surface water on 

 the 22nd of February eight miles west of Utsire (West Coast Spring 

 Herring Fishery District) had a salinity of 34*01 per thousand. The 

 plankton consisted principally of the Copepods Calanus finmarchicus 

 and Pseudocalanus elongatus, Sagitta, species of Coscinodiscus and 

 Chcctoceros decipiens (cf. also the plankton obtained on the 28th February 

 in bank water, having the high salinity of 33'92 per thousand). 



The general tendency of Hjort's results, considered by themselves, 

 appears to be towards the following conclusions : — 



(1) Cilioflagellates (especially Ceratium tripos) are particularly 



characteristic of Baltic water {i.e., water of very low salinity). 



(2) Diatoms of the genus Chcctoceros are particularly characteristic 



of bank water of rather high salinity (33 per thousand). 



(3) Diatoms of the genus Coscinodiscus, in the absence of Cilioflagel- 



lates, are particularly characteristic of bank water of still 

 higher salinity (33-5 per thousand to 33"9 per thousand) and of 

 North Sea water (34 per thousand). It will be remembered in 

 this connection that in the winter of 1894, when Coscinodiscus 

 was so plentiful, North Sea water was found on the surface a 

 very short distance from the west coast of Norway, while in 1895 

 the absence of Coscinodiscus from the plankton was correlated 

 with the great superficial extent of bank water of low salinity. 



* The salinity and temperature are taken from the hydrograpliic tables, p. 61, not from 

 the tigures given in the plankton tables, p. 48, which are clearly erroneous. The figures 

 given in the latter table apjiear to have been accidentally transferred from the hydrographic 

 record for station 297, January 26th. 



NEW SERIES. — VOL. V. KO. 1. E 



