576 ■ I^- Stephensen. 



Channel; the occurrence of these last-mentioned forms in boreoarctic 

 regions shows already, that they can live in water-layers, which 

 form a transition between the Gulf and Polar Streams; with such 

 a mixed layer they can thus be carried into the Norwegian Channel, 

 where they have adapted themselves to more boreal conditions". — 



It seems to me of much interest, that there are several species 

 of the cold area which may occur in quite shallow water, if only 

 the temperature is sufficiently low: Bythocaris simpliciroslris 30 fm. 

 (E.Greenland), Siegocephalus inßatus 5 — 20 fm. (E.Greenland), Bathy- 

 medon ohtiisifrons 48 fm. (W. Greenland), Cleippides quadricaspis 50 fm. 

 (E. Greenland), Halice abyssi 10 — 20 fm. (E. Greenland), Erichtonius 

 megalops 48 fm. (W. Greenland), Caprella horrida 30 fm. (Hudson Bay), 

 Caprella microtuberculaia 10 — 95 fm. (Franz Josephs Land), Anceus 

 elongatus 4^11 fm. (E. Greenland), Arcturus Baffini 10 — 90 fm. (E. Green- 

 land) Ilyarachna Bergendahli 20 fm. (Spitzbergen), Cryptocope arctica 

 15 — 20 fm. (E. Greenland), Boreonymphon robustum 5 — 25 fm. (E. Green- 

 land) and Colossendeis angusta 12 — 18 m. (E. Greenland). It thus 

 appears, that the absolute depth is of no importance or ar least very 

 little, if only the hydrographical conditions, especially the tempera- 

 ture, is suitable. Dr. Th. Mortensen mentions also (Danmark Exped. 

 Echinoderms p. 293) a similar condition among the Atlantic deep- 

 water fauna, as 6 typical, Atlantic-archibenthal Echinoderms are 

 found at the Norwegian coast in 20 — 60 m. 



The fact, that a number of the species of the cold area are 

 found in shallow water at East Greenland seems to me to suggest 

 an explanation of the conditions in the arctic deep basin at West 

 Greenland. Dr. Mortensen writes certainly (1. c, p. 293) that "the 

 Polar Deep-Sea is so sharply separated from the Baffin basin through 

 the shallow waters in Smith Sound and the other sounds to the 

 North of Baffin Land, that a direct communication of the deep-sea 

 fauna of the Polar Sea with that of the Baffin Sea is excluded. If 

 a nearer relation between the deep-sea faunas of these two regions 

 proves to exist, it must be due to a more direct communication in 

 a former period." But when so many species comparatively can live 

 in relatively shallow water, it cannot be denied, that the connection 

 between the animal-world of the two seas, in spite of the shallow 

 depth in Smith Sound, must be considered probable. The deep-sea 

 animals of Baffins Bay must have wandered in from the depths of 

 the Polar Sea through Smith Sound and the other sounds N. W. of 

 Greenland. 



Some of the certainly arctic, deep-water Malacostraca are found 

 (apart from the Norwegian Channel) outside the southern boundary 

 of the region. A few are taken in Davis Strait south of the ridge: 



