342 Annals of the South African Museum. 



conical granules ; all over the radial shields, which are about 2-5 mm. 

 long and distally 1'5 mm. wide, and also on the interradial margin 

 between the distal ends of the pairs of radial shields, are numerous 

 granules about "10 mm. in diameter: these are well spaced, and 

 even irregularly scattered except at distal ends of the radial shields 

 where they become somewhat crowded to form the uniform granular- 

 coat which covers the upper surface of the arms; in each inter- 

 brachial area are scattered a dozen or more granules, of which 

 about half are conical and pointed, -25-'50 mm. high. No upper 

 arm-plates; distally the granular covering of the arms becomes less 

 and less continuous, until there is only bare skin with a few scat- 

 tered granules on each segment. Interbrachial areas below, perfectly 

 naked except for a very few conical granules. Oral shields, adoral 

 plates and under arm-plates wanting or apparently so, for if present 

 they are completely obscured by the thin skin. Oral plates large 

 and dental papillae numerous. No oral papillae, of course. Base of 

 each jaw perforated as in Ophiothrix. Side arm plates short, about 

 as high as arm, compressed into a spine-bearing ridge, which carries 

 6 or 7 short, blunt, not very thorny spines; uppermost and three 

 lowest spines smallest, third longest and equal to an arm-segment; 

 the lowest does not become hook-like until near tip of arm. No 

 tentacle scales but the tentacles are protected by the basal part of 

 each side arm-plate. Colour of dry specimen, pale salmon, the bare 

 skin browner and the granules whiter. 



P.F. 10975. Tongaat River, N.W. by N. '/-', N., 5 miles, 36 fms. 

 S. and sh. 1 specimen; very young. 



P.F. 10976. Same locality as 10975. 1 specimen; adult. 



Holotype, South African Museum no. A 6440, P.F. 10976. 



This species differs very noticeably from 0. semperi in the much 

 coarser granulation of the dorsal surface, the large areas of naked 

 skin and the conspicuous radial shields. The last two characters 

 serve to distinguish it also from 0. rugosum, the only other member 

 of the genus. 



The specimen from P.F. 10975 has obviously undergone fission as 

 it has six arms, three of which, with their associated radial shields, 

 are much smaller than the others. At first glance it resembles an 

 Ophiothela but more careful examination shows that the side arm- 

 plates are not like those of that genus. In colouration it is very 

 similar to the adult. The upper surface of the arms, however, even 

 at the base, is not uniformly granular but has few, irregular, unequal 

 scattered granules on each segment, much as in Ophiothela, and just 

 as on the terminal segments of the arms of the adult. 







