392 Annals of the So-nth African Museum. 



Key to the South African Species of Clypeasteridae. 



Test about as wide as long, pentagonal with more or less concave sides; petals 

 narrow with only slightly convex poriferous areas . . Clypeaster audouini. 



Test longer than wide, ambitus more or less elliptical ; petals rather wide, with 

 more or less obovate interporiferous area and strongly convex sides 



Clypeaster humilis. 



* CLYPEASTER AUDOUINI. 

 Fonrtau, 1904. Bull. Inst. Egypt, ser. 4, no. 4, p. 418; pi. I, figs. 1-3. 



There are in the M. C. Z. collection three very good specimens of 

 this well-marked species, which \\cre presented by Dr. Robert T. 

 Jackson, who purchased them in London. They were labelled as 

 having come from Durban, Natal. Fourtau's specimens were from 

 the Red Sea, so the species would seem to be characteristic of the 

 whole Eastern coast of Africa. 



CLYPEASTER HUMILIS. 



Echinanthus humilis Leske, 1778. Add. ad Klein, pp. XIX, 121. 



Clypeaster humilis A. Agassiz, 1872. Rev. Ech., pt. 1, p, 100. 



H. L. Clark, 1914. Mem. M. C. Z., vol. 46, p. 36; pis. 137; 138, fig. 4. 



Although this species has long been known from Mauritius it has 

 not been recorderd hitherto from the African coast. A small clype- 

 astroid in the M.-C. Z. collection, supposed to be from Durban, Natal, 

 seems however to represent this species, altlio it may not be denied 

 that it is possible it is a young audouini. The test is 36 mm. long 

 and 34 mm. wide, so that a very slight change in the rate of growth 

 of either axis might make a perfectly pentagonal test. The petals 

 however are relatively wide with strongly convex poriferous areas. 

 In spite of the petals, I should call this specimen a young audouini, 

 were it not for the PIETER FAURE specimen. This is a much younger 

 individual, 18 mm. long and 16 mm. wide, with relatively wide petals 

 having strongly convex sides. It seems to me unlikely that the 

 young of audouini would be less pentagonal than the adult, or that 

 its petals \vnuld be so wide. As humilis probably occurs on the 

 African coast, it seems to me better to list these two young clype- 

 astroids under that, name, especially as they agree with a young 

 Jut in His from Ceylon, in practically every particular. 



P.F. 12084. O'Neil Peak, N.W. Vi W., 9 miles, 90 fms. Brk. sh. 

 1 specimen ; very young. 



