The Echinoderm Fauna of South Africa. 253 



of these four appear to be new. The following key shows how easily 

 the South African goniasterids can be distinguished from each other. 



Key to the South African Species of Goniasteridae. 



Abactinal surface of disk covered with pseudopaxillae or granule-bearing tabula. 

 Rays more or less elongated; R more than 2 r. 



Each inferomarginal with 1 3 small, more or less appreesed spinelets; 

 no true (alveolar) pedicellanae present. 



R = 3 4r; superomarginals occupy less than */ r;.paxillar area at 

 base of arm about '60 of arm-width . Pseudar chaster tessellatus. 

 R = 2 2'5 r; superomargmals occupy '/3 r ! paxillar area at base of 

 arm about '40 of arm -width . . Pseudarchaster brachyactis 



No spinelets on inferomarginals ; at least a few true pedicellariae present 



Mediaster capensis. 

 Rays short, form more or less pentagonal; R less than 2 r. 



Interradial superomarginals squarish, often longer than wide, but occa- 

 sionally wider than long; distal subambulacral spines not conspicuously 

 enlarged. 



Inner ends of interradial superomarginals distinctly squarish; their 

 length equals or exceeds width; paxillae granules very close set, the 

 marginal series with vertical outer sides Ceramastcr chondriscus. 

 Inner ends of interradial superomarginals markedly rounded; their 

 width exceeds length ; paxillae granules rounded and not close-set 



Ceramaster trispinosus. 



Interradial superomarginals nearly twice as wide as long; distal subambu- 

 lacral spines conspicuously enlarged Ceramaster patagonicus, var. euryplax. 

 Abactinal surface of disk with no pseudopaxillae or distinct tabula. 



Actinal intermediate plates, each with a heavy spine, more or less elongated. 

 Pedicellariae wanting; adambulacral furrow series of 3 or 4 stout spines 



Calliaster baccatvs. 



Pedicellariae present; adambulacral furrow series with 6 9 slender com- 

 pressed spines ..... Calliaster acanthodes. 

 Actinal intermediate plates with granules, tubercles and pedicellariae, but no 

 spines. 



No marginal plates with spines or conspicuous tubercles Tosia tuberculata. 

 Many marginal plates with tubercles or stout spines. 



No disk plates with stout capitate spines or big central tubercles 



Cladaster macrobrachius. 



Many disk plates with -stout capitate spines or big central tubercles 



Hippasteria phrygiana. 



PSEUDARCHASTER TESSELLATUS. 

 Sladen, 1889. CHALLENGER Ast., p. 11 1 2: pi. 17, figs. 3, 4 



The specimens at hand (R = 32-50 mm.) are about the same size 

 as Sladen's (R = 48 mm.) and answer very closely to his description. 

 There is however a median unpaired spine at the tip of the jaw 



17 



