532 DEPTHS OF THE OCEAN 



as inlets, while their landward portions are cut off by submarine 

 barriers which are often comparatively shallow. As a con- 

 sequence the warm water of the Gulf Stream flows along the 

 bottom of the fjords till it reaches the barriers, but is unable to 

 penetrate into the inner basins, which are therefore greatly 

 affected by climate, their water-masses at comparatively shallow 

 depths being stagnant and at a low temperature. We find 

 accordingly an arctic fauna predominating in the inner basins, 

 while the boreal forms met with on the coast and in the sea- 

 ward portions of the fjords in corresponding depths are for the 

 most part absent.^ Still there are arctic forms in these latitudes 

 along the coast in the shallow waters of the littoral (and sub- 

 littoral) zones, where climatic conditions occasion low tempera- 

 tures for at any rate part of the year. The fauna at greater 

 depths along the coast, on the other hand, is purely boreal 

 owing to the influence of the Gulf Stream. We are accord- 

 ingly justified in regarding Lofoten as the southern limit of the 

 boreo-arctic area, so far as the coast tracts are concerned, 

 even though the boreal element preponderates there, and 

 similarly we are entitled to call the inner basins of the fjords 

 boreo-arctic, although in their case it is the arctic element that 

 predominates.- 



The coastal areas and fjords east of the North Cape (East 

 Finmark) are altogether boreo-arctic. The fjords here are open 

 arms of the sea, in which there is no distinction between the 

 fauna of the outer and of the inner portions, and, owing to the 

 intermingling of Gulf Stream and polar waters, the purely boreal 

 character of the fauna predominating in West Finmark is absent 

 even in the deeper parts. Moreover, the farther east we go and 

 away from the influence of the Gulf Stream the more do these 

 conditions assert themselves, the fauna becoming gradually 

 more and more purely arctic. A comparison between this area 

 and large parts of one of the best-known areas in high arctic 

 latitudes, namely Spitsbergen, shows how perfectly justified we 

 are in calling it boreo-arctic, for we find a fauna on the Murman 

 coast which, in addition to purely arctic species, includes littoral ^ 



^ G. O. Sars, " Some Remarks on the Character of the Marine Fauna along the Northern Coasts 

 of Norway," Tromsd Museums Aarshefter II., 1879, p. 60; Nordgaard, Hydrographical and 

 Biological Investigations in Norwegian Fjords, Bergen, 1 905. 



^ It must be distinctly stated, however, that this fauna is made up mainly of forms which, 

 although undoubtedly of arctic origin, are distributed over both the boreal and arctic regions ; 

 whereas the purely arctic forms are comparatively few. These Qord areas are entitled to be 

 characterised as boreo-arctic owing to the presence of a small number of purely boreal forms 

 with boreo-arctic distribution otherwise. 



^ Purpura lapilhis, Littorina littorea, Nacella pellucida, Mytilus edulis, Tellina baltica, 

 Asterias rubens, Balaiius balanoides, Crangon vulgaris, Dynamena puinila. 



