366 EIGHTH PACIFIC SCIENCE CONGRESS 



distribution of the Echinoderms, and special fauna elements in certain 

 regions will probably mostly prove to be olf-shoots of neighbouring 

 archibenthal regions." 



To get such different opinions to meet is very difficult at a time 

 when much new evidence is under way, e.g. from The Swedish Deep 

 Sea Expedition 1947-48 in the North Atlantic (NybeHn 1951, 1953), 

 from the Russian investigations in the North West Pacific (Zenkevitch 

 1953), and from the Danish Galathea Expedition Round the World 

 1950-52 (Bruun 1951, 1953a, 1953b, Dahl 1953, Gislen 1953, Kirkegaard 

 1953, Madsen 1953, ZoBell 1953). At present it can only be done in 

 a sketchy way, by putting forAvard some postulates for further examina- 

 tion. It should also be emphasized that very much more collecting 

 must be carried out even if the deep-sea expeditions after 1945 have 

 brought knowledge a step forward. 



As true abyssal animals only species which breed regularly at depths 

 exceeding 2000 meters should be considered. Very little is known about 

 the reproduction of abyssal animals, but it may be expected that cer- 

 tain species breeding on the continental slopes may have juvenile stages 

 carried by currents to dee|Der water, where they can live but not breed. 



A parallel example would be the abyssal records of the deep-sea 

 eel SynapJiobrcmchus; different species of this genus have been found 

 in all oceans, from the Arctic Circle in the Atlantic to the latitudes of 

 New Zealand in the Pacific. But the distribution is governed by the 

 epipelagic breeding-places, which seem to be much the same as those 

 of the freshwater eel {Anguilla), as shown by the distribution of the 

 leptocephali of both genera (Bruun 1937). 



Some examples of how scanty is our knowledge of the deep-sea 

 animals may be given. The polychaete Nepthys elameUata Eliason was 

 found only in 1948 in the North Atlantic at 4270 and 4600 meters by 

 The Swedish Deep-Sea Expedition; it was found again in the Pacific 

 in the Kermadec Deep (Kirkegaard 1953) at 6140-6960 meters. 



The elasipod holothurian Elpidia glacialis Theel which has been 

 considered as one of the most typical species of the Arctic Ocean, was 

 taken by the Galathea in several localities in the Java and the Banda 

 Deeps and in one of the hauls in a number of about 3000 specimens 

 (Madsen 1953). From the Banda Deep at a depth of 7250 meters 

 may also be mentioned the depth record of the irregular echinoid Poiir- 

 talesia aurorae Koehler caught by the Galathea, while this species was 

 only known formerly from the Antarctic from 440-1690 meters (Mad- 

 sen 1953). The same author also gives the Galathea finds of another 

 peculiar irregular echinoid genus EcJiinosigra (which hitherto was 

 known only from the North Atlantic and the Atlantic sector of the 



