534 DEPTHS OF THE OCEAN chap. 



I have already stated that the north and east coasts of 

 Iceland are boreo- arctic areas. Even as far south as lat. 

 64° 17' N. and long. 14° 44' W., that is to say, quite close in to 

 the coast, the " Michael Sars " found purely arctic forms at a 

 depth of 75 metres, namely, the prawn Sclerocrangon boreas and 

 the ascidian Molgula retortifoinnis, together with forms that are 

 either widely distributed throughout both regions, or are boreal 

 with a boreo-arctic distribution.^ Here again, therefore, the 

 character of the fauna was evidence of the meeting of the 



two great currents, the 

 East Iceland Polar 

 Stream and the At - 

 lantic Stream. 



Before leaving the 

 arctic fauna I have 

 still to mention a few 

 characteristic forms, 

 which penetrate for a 

 short distance into the 

 boreal region along the 

 coast of Norway. The 

 starfish Ctenodiscus 

 crispatus is found as 

 far south as Christian- 

 sund, where it occurs 

 in enormous quanti- 

 ties; and another star- 

 fish, Leptoptychaster 

 arctictisi' has its south- 

 ern limit in the Trondhjem fjord. A very characteristic arctic 

 species of mussel, Peden islandiais (see Fig. 374), is very 

 numerous and of large size in the Trondhjem fjord, and may 

 be met with even farther south, while the same fjord is the 

 southern limit for the molluscs Onchidiopsis glacialis, Dendro- 

 notus velifer, and a few others. We have thus another instance 

 of the difficulty in fixing definite boundaries for the different 

 regions. The Trondhjem fjord shelters too many forms which 



^ I append tlie names of a few forms : — Ascidians : Ascidia obliqiia, Peloiiaia roryugata, 

 MacrocUnum poinunt (numerous), Distoma aystallimim. Crustaceans : Hyas coairtaitis, 

 Pagurus, Pandaliis atimdicornis, Hippolyte polaris, Crangon allnianni, Arciurus sp. Echino- 

 derms : Asterias ricbens, Echiuaster sanguinolentus. Pycnogonids : Pycnogonum littorale, 

 Nytnphon mixtum, N. hirtipes. Coelenterates : Metridium dianthus, Cory7norpha glacialis, 

 Ttibularia indivisa (common), Hydrallmannia falcaia, and a few other hydroids. Also some 

 sponges and worms. 



^ The peculiarity about this form is that it lives mainly in boreo-arctic areas, and is thus 

 neither purely arctic nor purely boreal. 



Fk;. 374. 

 Pecten islandicus, L. Reduced. 



\fter G. O. Sars. ) 



