viii Transactions of the South African Philosophical Society. 



at once be assumed that this is due to the different character 

 of the waters. We will find, however, as for instance in the 

 last-mentioned feature, that this is far from sufficient. A key to 

 a fuller illustration is found when we consider the general dis- 

 tribution of this marine fauna, and the affinities of its component 

 elements to the general marine fauna of the globe. For this pur- 

 pose we will now direct attention more to the distribution of the 

 strictly pelagic or oceanic forms. One of the most obvious instances 

 is found in the general distribution of the Snoek (Thyrsites aturi) 

 which we have already taken to illustrate another point. It is found 

 in abundance on the Chilian coast of South America, at Tristan 

 d'Acunha, on the west coast of South Africa, and on the west coast 

 of Australia — that is, on those coasts on which the Antarctic drift 

 current impinges. It is therefore a form which is characteristic of 

 the west wind current. There are other forms of the South African 

 fish fauna such as the general Bdellostoma, Agriopus, Callorhynchus, 

 which link it on to the regions traversed by this current, and 

 those general in South African waters, like the Snoek, seem to be 

 most characteristic of the west and south coast. On the other 

 hand, there are a number of forms growing more numerous 

 towards the west which show a great affinity with the warmer 

 waters of the Indian Ocean. Thus the well-known Blaasop 

 (Tetrodon lionckenii) is a representative of the tropical Gymno- 

 donts. It is found in abundance in False Bay, but seldom in 

 Table Bay, though it is found in Hout Bay. One or two other 

 members of the group are occasionally found in False Bay, and 

 they become much more abundant towards the east coast. There 

 also such forms as Pterois, Apistus, &c, have been found, while the 

 Squamipinnes increase in numbers and species. The same fact is 

 illustrated in the flat fishes. 



The affinity with tropical Indian Ocean forms is, like the previous 

 case, readily understood by the intimate connection with that region 

 brought about by the warm current of the east coast, and we are 

 not surprised to find that regions of the same latitude on the west 

 coast are entirely devoid of these forms. When, however, we find 

 in the Cape seas Zeus japonicus and Monocentris yaponicus, forms 

 characteristic of Japanese waters, it is more difficult to realise that 

 the distribution can be accounted for by currents connecting the 

 two regions, though I would again remind you that there are no 

 insuperable land barriers between the Indo-Pacific coast and 

 that of South Africa. There is, however, another element in the 

 South African marine fauna much more difficult to account for, 

 and one which, from evidence now accumulating, seems to be a 



