The Echinoderm Fauna of South Africa. 367 



are three or four others, which are possibly only stragglers south 

 of that point. 



Of the 17 continental echini, we find that there are 11 which 

 are endemic. This includes Spatagobrissus and one other species 

 hitherto undescribed. Of the 6 species not endemic, only two are 

 Indo-Pacific, one is distinctly southern, occurring oil the coasts of 

 both southern South America and southeastern Australia, one is 

 West Indian and tw^o are well-known North Atlantic forms. It 

 ought to be added further that of the 11 endemic species, no fewer 

 than 7 are nearly allied to north Atlantic or West Indian species. 

 It is quite clear then that a very large proportion of the continental 

 Echini of South Africa came from the west rather than from 

 the east. 



Of the 4 abyssal echini, one is endemic, one is distinctly antarc- 

 tic (in deep water), one is North Atlantic and one is cosmopolitan. 



We may conclude then that the South African echinoid fauna 

 contains three distinct elements at least. First, an important Indian 

 and Indo-Pacific element which makes up most of the littoral group. 

 Many of these species do not occur south of Durban and a con- 

 siderable number are only stragglers south of the vicinity of Mozam- 

 bique. Only two are endemic and one of these is a persistent relict 

 of a group, geologically very old. A second element in the South 

 African fauna is from the North Atlantic and the W T est Indian 

 region. This makes up nearly the whole of the continental fauna, 

 and has one representative in the littoral and one in the abyssal 

 group. Many of the continental forms have become sufficiently 

 differentiated to be specifically distinguishable from their nearest 

 allies but there is little doubt .of their original stock. The third 

 element in the fauna is austral and is relatively insignificant, being- 

 represented by only one abyssal and one continental species. The 

 echini therefore add to the weight of evidence that the South Afri- 

 can echinoderm fauna has received its littoral element from the 

 east and its continental element from the w^est. 



The 44 species of sea-urchins here listed belong to no fewer than 

 21 families. The Palaeopneustid<te. is the only one of the other eight 

 families of Echini large enough to make its absence worthy of com- 

 ment. The 21 families are distinguishable from each other as 

 indicated in the following kev. Under each family will be found a 



i 



key to its South African species, when more than one occurs in the 

 area covered by this report. 



