226 Annals of the South African Museum. 



group and of these 55 are endemic, about the same percentage as 

 among the littoral species. But the remaining 43 species show very 

 little Indo- Pacific connection. Only half a dozen are really species 

 of that region, while at least 15 are from the Atlantic and a dozen 

 more are distinctly austral. The remainder are more or less cosmo- 

 politan. When we examine the 55 endemic species we find that 

 their nearest relatives are very largely Atlantic Ocean or West Indian 

 forms or at least they belong in genera occurring in the Atlantic. 

 It seems clear then that the deeper water fauna of the Cape region 

 has not come in from the east but has largely come from the west 

 and north, with the addition of a considerable austral element, the 

 significance of which is not clear. 



Examination of a chart showing the ocean currents on the coasts 

 of South Africa suggests that they have been a determining factor 

 in the development of the echinoderm fauna of the region. The 

 warm Agulhas current has brought the shoal water Indo-Pacific 

 fauna clear to the Cape itself but the further south and west this 

 fauna has been carried the more it has become modified until no 

 truly Indo-Pacific species occurs at the Cape itself. The Benguela 

 current flowing northward along the western coast has effectually 

 prevented any influx of northern littoral species from the Atlantic. 

 The few notable exceptions such as Ophiothrix fragilis and Ophioderma 

 leonis (an endemic species of a West Indian genus) may perhaps be 

 accounted for as the result of artificial introduction, for example on 

 the foul bottom of a sailing vessel. It is worthy of note that the 

 cold winter water at the Cape, westward of the bend in the Agulhas 

 current, has acted as a very effective barrier in preventing any con- 

 siderable extension of the echinoderm fauna of Natal and southeastern 

 Cape Colony up the west coast. The west coast fauna as revealed 

 by collections at Saldanha Bay and Angra Pequena is a small one 

 made up of about sixteen species, of which only one (Parechinns 

 angulosus) is known from east of Algoa Bay. 



On the other hand the great surface currents seem to have had 

 little to do with the development of the deeper water fauna, which 

 seems rather to suggest changed continental boundaries. The very 

 evident relation of this fauna to that of the North Atlantic and the 

 West Indies is difficult to account for with the present ocean depths 

 and their boundaries as they are to day. Moreover the distinct and 

 considerable austral element suggests the possibility of former con- 

 tinental lines to the south very different from those of to day. And 

 finally the considerable percentage of widely distributed, if not cos- 

 mopolitan, species, such as those occurring in the North Pacific, 



