298 Annals of the South African Museum. 



* RETASTER CRIBROSUS. 



Pteraster cribrosus von Martens, 1867. Areli. f. Naturg., Jhrg. 33, Bd. 1, 



p. 109; pi. 3, figs. 2-2c. 

 Belaster cribrosus Sladen, 1889. CHALLENGER Ast., p. 477. 



When Perrier instituted his genus Retaster in 1878, he gave a 

 very indefinite diagnosis, mentioned no species by name and speedily 

 forgot his own creation, ignoring it entirely in his faunal lists. Sladen 

 revived it and added a number of species but so far as I know no 

 type has ever been designated and all workers have found it difficult 

 to draw a satisfactory line between Retaster and Pteraster. If how- 

 ever we take cribrosus as the type (and I herewith so designate it), 

 the difficulty greatly diminishes, if it does not wholly disappear. For 

 R. cribrosus is a well-marked form, easily distinguished from typical 

 Pteraster by the nature of the supradorsal reticulum, which is made 

 up of ligamentous bands, becoming quite hard when dry, though 

 apparently not calcified. Each mesh of the reticulum is a sharply 

 defined spiracular area, with numerous small spiracles. The adam- 

 bulacral plates are like those of Ptf raster and similarly armed with 

 a transverse webbed comb but the actinolateral spines are notably 

 short. If we accept the character of the dorsal reticulum as the 

 real basis for generic separation from Pteraster, we find that Retaster 

 is a small genus with few species. Sladen lists seven species but of 

 these only insignis seems to me congeneric with cribrosus, although 

 gibber may perhaps also belong with them. Aside from these, I find 

 no representatives of the same type of structure among all the species 

 of Pterasteridae known. The other so called Retasters should, I think, 

 be relegated to Pteraster. Von Martens records cribrosus from Mozam- 

 bic|ue but it is not known from south of that point. It seems to be 

 one of the characteristic sea-stars of Zanzibar. 



PTERASTER CAPENSIS. 

 Plate IX. Figs. 3, 4. 



Gray, 1847. Proc. Zool. Soc. London, p. 83. 



Bell (1905) records this species under the name Retaster capensis 

 from seven stations on the South African coast chiefly in shallow 

 water. But he gives no data whatever in regard to the specimens. 

 In the collection sent me are two large Pterasters from False Bay 

 (one of the stations noted by Bell) labelled "Retasler capensis' 1 ? With 

 these is the note: "We have no specimens of Retaster capensis bearing 

 numbers similar to those given by Bell, but two supposed specimens 



