PHYSICAL AND BIOLOGICAL CONDITIONS IN THE NORTH SEA. 237 



The first-mentioned is known to be the principal food of the great 

 whale, Balenoptera Sibhaldii, and is most abundant between Varanger 

 Fjord and the Lofoten Islands. The herring fishery was then going on 

 in the neighbourhood of Lysekil. Only 33 per cent, of the herrings 

 caught had any food in their stomachs, and it consisted of 15 forms of 

 animal Plankton, of which the remains of Limacina balea was the 

 most remarkable. This Pteropod frequents chiefly the North Atlantic 

 and Arctic Ocean, and occasionally appears on the west coast of 

 Norway, where it is greedily devoured by herrings. As not a single 

 specimen of the species was found in the waters of the Skagerack 

 in November, the shells of the Limacina in the stomachs of the 

 herring must have been a remnant of the food swallowed by the fishes 

 outside the Skagerack. The winter herring are caught in water of the 

 kind denoted here as northern coast water, and disappear with it. 



The northern species of fish mentioned by Mobius and Heiucke as 

 occurring occasionally in the Baltic are : — Ziparis Montagui, Montague's 

 Sucker; Anarrhichas lupus, the Cat-fish; SCichaeus IslandiciLs; Gadus 

 pollachius, the Pollack ; Hip)poglossus vulgaris, the Halibut ; Plcuronectes 

 cynoglossus, the Witch ; Gadus virens, the Coal-fish ; Lota molva, the 

 Ling ; Raia radiata. 



According to Pettersson these northern fishes are only found in the 

 Western Baltic in the early part of the year, that is to say, chiefly in 

 January, February, and March, during the time when, as he has proved, 

 there is an inflow of coast water of a temperature of 4° to 6° C. along 

 the south coast of Norway into the Skagerack and Cattegat. 



Having analysed with so much success the composition of the waters 

 entering and leaving the Baltic, Professor Pettersson and the Swedish 

 hydrographers associated with him, conceived the project of extending 

 the application of their methods to the whole of the North Sea, in 

 order to distinguish the different waters entering and leaving that 

 basin, and to trace them to their sources. Proposals were accordingly 

 made to the governments of other countries bordering the North Sea, 

 that they should take part in an international co-operative hydrographic 

 survey. On behalf of Britain the Scottish Fishery Board undertook to 

 survey the region to the north and east of Scotland. In accordance 

 with the plans arranged, H.M.S. Jackal was employed in the work, and 

 Mr. H. N. Dickson, F.R.S.E., was entrusted with its execution. Four 

 expeditions to the northern entrances to the North Sea were made — in 

 August and November, 1893, and in February and May, 1894. The 

 results of the observations are recorded in detail in the Twelfth Eeport 

 of the Scottish Fishery Board; and in Natural Science for January, 1895, 

 Mr. Dickson published an article in which he discussed the probable 

 influence of the movements of water which had been ascertained to 



