The Echinoderm Fauna of South Africa. 377 



Pedicellariae fairly abundant, but only two kinds were noted, 

 ophicephalous and tridentate. The former are characteristic having the 

 markedly constricted valves found in cubensis, mirabilis and pulchellu, 

 but different from those of any of these species in the wider blades 

 and the more abrupt contraction between blade and base; a typical 

 valve is about '27 mm. long, with the loop '10 mm. more; the ex- 

 panded part of blade is about -17 mm. wide and "11 long, while the 

 base of the valve is "19-'20 mm. wide. The tridentate pedicellariae 

 are not abundant nor do they seem to reach a large size; the valves 

 are always straight and narrow and are more or less expanded, as 

 well as in contact, at the tip; the largest ones noted were '80 mm. 

 long. The ophicephalous pedicellariae are most common abactinally 

 while the tridentate occur chieily on the coronal and buccal plates. 

 The calcareous plates of the tube-feet are very numerous, coarsely 

 reticulated, often narrow with drawn-out, rod-like ends. 



Colour of test, dried from alcohol ; dingy whitish, but whole genito- 

 ocular ring and the coronal plates immediately adjoining rich bright 

 purple in abrupt contrast; periproct very pale violet or at center, 

 whitish. Secondary spines whitish but the primaries above the am- 

 bitus are more or less markedly purple, though the basal portion 

 may be dull flesh-color or reddish. 



P.F. 16902. Cape Point, N.E. by E. V 4 E., 40 miles, 800-900 fms. 

 Gn. m. 1 specimen; young. 



P.F. 17215. Cape Point, N. 77 E., distant? miles, 660-700 fms. 

 Gn. m. 2 specimens; small adult and young. 



Holotype, South African Museum no. A 6432. P.F. 17215. 



This very interesting sea-urchin is closely allied to C. hawaiiensis 

 from the Hawaiian Islands, but careful comparison shows a number 

 of differences of more or less value. Perhaps the most important of 

 these are in the ambulacra, which are composed of fewer and wider 

 plates; thus, in a specimen of hawaiiensis of the same size as the 

 holotype of capensis, there are 10 or 11 ambulacra! plates and 8 inter- 

 ambulacral, as against 9 of each in the African species; moreover 

 the ambulacra are only about half as wide as the interambulacra, 

 while in capensis they may be four-fifths as wide. Another difference is 

 in the position of the genital pores, which are much further from 

 the distal angle of the plate in capensis than in hawaiiensis. The 

 periproctal plates in capensis are very thin and overlapping, while in 

 hawaiiensis they are much more like granules. The ophicephalous 

 pedicellariae in the two species are quite unlike. Although both 

 species are conspicuously purple abactinally, the contrast between the 

 purple and the dingy white of the greater part of the test is quite 



