CHAP. IX PELAGIC ANIMAL LIFE 639 



bay of open water runs for an unknown distance towards the 

 north. 



The vertical distribution of the cold water in the Norwegian 

 Sea along a line from Greenland past Jan Mayen to Vesteraalen 

 is shown in Fig. 310, p. 436, which indicates that the great 

 body of water in the Norwegian Sea has a temperature below 

 2° C., and that warm water is found only in the eastern part of 

 the sea towards Norway to a depth of 500 or 600 metres. 



The investigations of the " Michael Sars " have been 

 limited mainly to the area covered by this warm water, but a 

 thorough investigation of the arctic Greenland Sea has been 

 made by the Duke of Orleans in his expeditions on board the 

 " Belgica," in which Koefoed took part, and had the oppor- 

 tunity of making collections with the same appliances as were 

 employed on board the " Michael Sars." The " Belgica" and 

 " Michael Sars " material has been dealt with jointly by 

 Koefoed and Damas, upon whose treatise ^ I have drawn for 

 information about some of the most important arctic forms. 



Damas and Koefoed divide the Copepoda of the Greenland 

 Sea into several biological groups : (i) forms which live 

 mainly in the surface waters, such as Calanus finmarchicus and 

 C. Jiype7''boreus, Pse^idocalanus elongatus and P. gracilis, Onccsa 

 conifera and O. notopiis, Oithona similis \ (2) forms living 

 mostly in mid-water, but occasionally appearing at the surface, 

 atypical form being EuchcEta norvegica \ (3) mid -water forms 

 which never occur at the surface, especially Eiichceta glacialis ; 

 and (4) deep-sea forms, like Euchceta barbata, Chiridiella 

 7nacrodactyla, and others. 



At the surface the commonest form is Calanus kyperboreus, caiatms 

 one of the largest of copepods, attaining a length of 9 mm. h'perboreus. 

 At the ice it is found 5 to 10 metres below the surface in 

 enormous numbers. Thus in July a few hauls with closing nets 

 in lat. 75° 55' N, long. 9° W., depth 1275 metres, gave: — 



In a haul from lo to o metres, tooo specimens. 

 ,, ,, 100 to 20 ,, 2 ,, 



,, ,, 400 to 210 ,, 4 ,, 



It is mainly an arctic form, and occurs in the Polar basin, 

 in the Greenland Sea, and in the colder parts of the Norwegian 

 Sea. Its propagation takes place principally in the shallow parts 

 of the Greenland Sea, on the coast banks and not where the 

 water is deep, whence the young are carried out into deeper 

 water by currents. The wealth of animal life in the Arctic is 



1 Damas and Koefoed, loc. cit. 



