218 



TEMPERATURE. 



of those influences which obviously regulate, in 

 some degree, the distribution of marine life, and 

 the changes which they immediately produce. 



Foremost amongst these is the influence of tempe- 

 rature. The marine fauna which we have been here 

 considering occurs on a line of coast which, if limi- 

 ted to European countries, has an extension in lati- 

 tude of nearly 3000 miles, but which zoologically 

 extends from the Arctic basin to the Canaries. It 

 will be sufficient in this place to notice the winter 

 and summer temperatures of successive sections of 

 the Atlantic coast-line, and to connect these with 

 the condition of the internal seas. On the Russian 

 shores of the Arctic Ocean the mean cold for the 

 two winter months falls below 5° Fahr.* This is 

 the winter temperature of Spitzbergen, and the 

 coast is ice-bound from October till May ; yet here, 

 as we have seen, and at depths below the reach of 

 ice, there is a Molluscous fauna. 



Compared with this, the temperature of the west 

 coast of Scandinavia exhibits a great change, and 

 is comparatively mild ; from Cape North, nearly 

 as low as Bergen, the degrees of cold range from 

 23° F. to 32° (freezing), but, at which place, the 

 sea water does not freeze oftener than three times 

 in a century. The portion of the coast where the 

 lower temperature prevails, from Cape North to the 

 Lofoden Islands is that along which the character- 

 istic fauna of the Arctic basin reaches. 



* See on map the course of the blue lines. 



