ZOOGEOGRAPHICAL REMARKS 95 



The regions shown in Tables 2 and 3 may be defined roughly as follows : 



Antarctic region. The waters south of the Antarctic Convergence, the mean position of which hes between 50-55° S. 



West-Atlantic-antihoreal region. Comprising the south-western part of the Atlantic Ocean between the Antarctic 

 and Subtropical Convergences and off the east coast of South America as far north as Montevideo, between 50-55° S 

 and 35° S. 



West-Atlantic-tropical region. Comprising the waters off the American coasts between about 35° S and 35° N. 

 Within this region, Discovery Collections were made as far north as about 10° N, midway between Brazil and West 

 Africa. 



West-Atlantic-boreal region. Comprising the waters off the American coast from about 35° N up to Labrador. 



Arctic region. Comprising the waters north of the Boreal region. ^ 



East- Atlantic-boreal region. Comprising the waters of north-western Europe from the English Channel to the 

 north point of Norway. 



Mediterranean- Atlantic region. Comprising the Mediterranean Sea and the adjacent Atlantic Ocean between the 

 Bay of Biscay and the Cape Verde Islands. Within this area only four Discovery Collections were made, between 

 about 24° N and 39° N. 



East- Atlantic-tropical region. Comprising the waters off the west coast of Africa between about 15° N and Great 

 Fish Bay in 17° S. 



South-African region. Comprising the waters off the African coasts between Great Fish Bay on the west coast and 

 Durban, in about 28° S, on the east coast. 



East- African-tropical region. Comprising the waters oft" the east coast of Africa, north of Durban. No collections 

 were made by the Investigations in any other part of the Indo-West-Pacific-tropical region, between the years 1926 

 and 1937. 



Indo-West-Pacific-tropical region. Comprising the waters of the tropical Indian Ocean and the western Pacific 

 from the Polynesian Is. northwards to about 35° N. 



Indian-temperate region. Comprising the antiboreal belt north of the Antarctic Convergence and the subtropical 

 tract between South Africa and south-western Australia. 



South- Australian-New-Zealand region. Off the Australian coasts, south of about 30° S, and New Zealand. 



Pacific-boreal region. Comprising the waters north of 35" N in the western part; 25° N in the eastern part. 



East-Padfic-tropical region. Between southern California, about 25° N, and about 8° S, off northern Peru. 



Peru-North-Chilensic region. Comprising the waters between 8° S and 42° S. 



Of course Ekman's areas mainly apply to the fauna of the continental shelves; his divisions of the 

 oceanic regions are very wide and comprise only a warm-water region and one or two cold-water regions 

 in each of the three great oceans. It seems desirable, however, to distinguish between minor areas 

 also in the distribution of oceanic animals, especially for the epipelagic species, which are partly 

 exposed to the same currents as the neritic forms. Consequently, in Table 3 which shows the distribu- 

 tion of the epipelagic Leptolina and Trachylina, I have retained the same divisions for the Atlantic 

 Ocean as I have used in Table 2 for the distribution of the neritic forms. But I have condensed the 

 Indian-temperate and the South-Australian-New-Zealand regions into an Indo-West-Pacific- 

 antiboreal region, and have united the Peru-Chilensic region with the East-Pacific-tropical region, 

 because in these areas only such species were found as occur in tropical seas. This arrangement has 

 been adopted here to coincide with the areas covered by the Discovery Investigations ; in a general 

 zoogeographical discussion I might proceed otherwise. 



Bathypelagic species, which live under quite different conditions, are not limited to regions in the 

 same way, and in Table 4 it will be seen that I have condensed the distributional regions still further. 



1 The deep water-layers in the Davis Strait, west of southern Greenland belong to the boreal region ; the deep water-layers 

 in the Norwegian Sea belong to the arctic deep-sea area. 



