President's Address. iii 



Now there is one striking difference in the course of the two 

 currents in these regions. In the Indian Ocean there is no outlet 

 towards the north, and the whole mass of water is turned down the 

 South African coast, where it is known successively as the Mozam- 

 bique current, the Natal current, and the Agulhas current. The 

 Southern Atlantic current, on the other hand, is met in its course by 

 the projecting portion of South America, and is split up into a branch 

 which flows to the south along the coast of Brazil, and another 

 which is directed northwards into the Carribean Sea and the Gulf 

 of Mexico, the origin of that great current of the North Atlantic — 

 the Gulf Stream. A connection is thus established between the 

 waters of the temperate regions of the southern and the northern 

 hemispheres. 



These are the outstanding features of the circulation of the surface 

 waters of the ocean. There is yet another to be considered before 

 we can be in a position to thoroughly realise the peculiar features of 

 the seas round South Africa. It is found that there is a constant 

 drift of the waters of the southern hemisphere from the pole in 

 an easterly and northerly direction, thus forming a south polar drift 

 current or the west wind drift current, and this mighty current 

 moves between the antarctic circle and the parallel of 45° south round 

 the open waters of the southern seas unimpeded except by the 

 tongues of land projecting into those regions, viz., the continent of 

 South America, that of Africa, and to a less marked degree that of 

 Australia. The continent of South America projects far south 

 beyond the parallel of 50°, consequently a great portion of the 

 current is caught and deflected northwards along its western coast, 

 while the whole of its southern portion is laved by the cold water. 

 In the case of South Africa, however, which is situated in a much 

 lower latitude, a smaller portion of the current is caught and deflected 

 northwards along its western side, and it is not strong enough to 

 completely force back the warm equatorial current which is coming 

 south along its eastern side, though strong enough, however, at 

 times to bring icebergs from the Antarctic to within a short distance 

 of the South African coast. 



It will thus readily be seen, then, that the sea round the South African 

 coast exhibits an almost unique character and one of fundamental 

 importance, not only in oceanic circulation but, as I hope to show, 

 in the distribution of marine life. On the one hand it is connected 

 by currents with the seas to the eastwards, directly to the Indian 

 Ocean and indirectly to the Pacific, while on the other it is directly 

 connected to the South Atlantic by the deflected northwards-going 

 branch of the Antarctic drift, and more indirectly to the North 



