President's Address. ix 



characteristic feature. This is the presence of forms specifically 

 identical with some that occur in European waters. Such 

 anomalies of distribution are not rare. For instance, Giinther 

 has drawn attention to the fact that several of the genera, and 

 even species, in Japanese waters are identical with Mediterranean 

 forms, and similarly, Alcock has shown that the same phenomenon 

 occurs in the Indian Seas. To account for the first case Giinther 

 has advanced the hypothesis that at some time in the geological 

 history of continents there was a direct sea communication between 

 Japan and the Mediterranean, and Alcock has had recourse to 

 the same convenient and indeed not improbable explanation. The 

 familiar Stock-fish (Merlucius vulgaris) and the Maasbanker (Caranx 

 trachtirus) are examples from the group of the fishes illustrating 

 identity of Cape and European forms, and several other species 

 recently found in South African waters have proved to be iden- 

 tical. Even in the group of marine annelids and other inverte- 

 brates the same agreement has been observed. In the fishes the 

 affinity to the Mediterranean forms has been specially noted. In 

 drawing attention to the similarity of the Japanese and Mediter- 

 ranean forms Giinther has given a list of Japanese shore fishes of 

 which fifty-four genera are identical in both places ; of these thirty- 

 five have now been found at the Cape, where also three genera, 

 described in the list as peculiar to Japanese waters, have been 

 found. How is the presence of Mediterranean forms in South 

 Africa to be accounted for? Unfortunately we cannot have 

 recourse to an explanation that would postulate a former direct 

 communication in past geological times, elastic as such explana- 

 tions are, and we are* compelled to look about for further informa- 

 tion with regard to the existing means of distribution. I have said 

 " unfortunately " ; perhaps, however, further necessary search for 

 facts will in the long run lead to a truer solution. As you will have 

 observed, the direction in which the solution may be looked for is in 

 a more intimate knowledge of the connection between the waters 

 of the North and South Atlantic, and it is in this direction also that 

 we must first look for a solution of the much greater but cognate 

 problem of bipolarity, or the identity of Arctic and Antarctic forms, 

 and that, only after looking most carefully into the specific diagnoses 

 of authors. 



I have, however, wandered further than I intended into this 

 fascinating question of distribution, and have said enough to 

 direct your attention to the composite character of the South 

 African marine fauna. I will only mention two other cases 

 which seem to be of special interest. A certain Lamellibranch 



