686 EEPOKT OF COMMISSIONER OF FISH AND FISHERIES. 



of its southernmost points, where it was found throughout to be very 

 sharply defined from tlie warm area. The farther north one goes, the 

 less marked does this boundary appear, as the cold area gradually rises 

 from the deep, until in the Polar Sea it is even with the surface and 

 then also occupies the littoral region, thus entirely excluding the warm 

 area. The inner connection with the above-mentioned peculiar physical 

 conditions of the seas surrounding our coast has been made a great deal 

 clearer by the experience gathered during our journey, and an import- 

 ant contribution has been made to the meteorology of the sea in general. 

 A further explanation of these purely physical conditions is also of the 

 greatest importance to zoologists for the better understanding of the 

 different biological conditions of the sea; but as such an explanation 

 belongs to the phj^sico-meteorological observations, we shall confine 

 ourselves to the purely zoological side of the question. 



The character of the fauna in the cold area is purely arctic or glacial 

 without any southern specimens whatever, and some of our varieties 

 have already been identified with those gathered in the Polar Seas by 

 the Swedish, German, British, and American Polar expeditions. In a 

 higher latitude these animals, which in the sea traversed by us live only 

 below a depth of 400 fathoms, and are therefore essentially deep-water 

 varieties, live in comparatively shallow water, even up to the surface of 

 the sea. This interesting fact seems to confirm the opinion expressed 

 by several naturalists, that the distribution of animal life in the sea is 

 chiefly dependent on the temperature, whilst the depth has but little 

 influence on it. The purely arctic fauna found on our coast during the 

 glacial period, and which has left its traces in the older glacial shell- 

 banks, was gradually forced to retreat towards the deep, and this was 

 chiefly occasioned by a change of temperature, which of course would 

 be less perceptible in deep water. The place of this arctic fauna was 

 then taken by animals immigrating from the south. In the deepest 

 waters of some of our long and narrow fiords a remnant of this original 

 arctic fauna may yet be found. But it evidently ekes out a miserable 

 existence, which is sufficiently proved by the small size and crippled 

 appearance of the animals. Their ultimate extinction is probably only 

 a question of time. After the temperature of the sea has been studied 

 more thoroughly, this can be fully explained from purely physical 

 causes ; for the influence of milder climatic conditions has finally also 

 reached these deep waters of our fiords, so that even at a depth of 650 

 fathoms the average temperature is + 0° C, a temperature which must 

 certainly have a hurtful influence on the life of these arctic animals. 

 The temperature outside of our sea-banks, even at a much lower depth, 

 has, however, remained the same as it was in the glacial period here as 

 well as close to our coasts. And we consequently find here, although 

 remarkably far south, no sickly or crippled arctic or glacial fauna, but 

 one fully as luxuriant as that of the Polar Sea. 



The light which meteorology will be able to throw on some dark 



