The Echinoderm Fauna of South Africa. 259 



greatly reduced, and is entirely wanting on the large plates of the 

 interradial region of the larger specimens; it is evident on all the 

 plates of a specimen with R = 42 mm. On the inferomarginals, the 

 bare space is present though small on 5 or 6 plates on each side of 

 the interradius in this small specimen but is wholly wanting in the 

 larger specimens. It looks therefore as though with increasing age 

 and size, the marginal plates tend to become wholly covered with 

 granules. The number and distribution of the pedicellariae is very 

 variable; in the small specimen they are very few but in the larger 

 ones they are more abundant; in one of the latter, they are present 

 on a large proportion of the dorsal tabulae, and on all the supero- 

 marginals, except those near tip of ray, there is at least one, often 

 there are two and not infrequently, three; on most of the infero- 

 marginals too they are present, and even on the actiriolateral plates 

 a few are to be found ; in the region just back of the oral plates 

 are 3 or 4 pedicellariae notable for their large size, fully twice that 

 of those on the abactinal surface; on the adambulacrals, there seem 

 to be no pedicellariae. 



Actinolateral plates rather numerous and crowded but their out- 

 lines are very distinct at the center of each area, less so near mouth 

 and least so on the outer part of each ray; except near the mouth 

 and distally, the two series adjoining the adambulacrals are wider 

 than long and oblong; those at center of area are rhomboidal; else- 

 where they are irregularly polygonal or rounded; the granulation is 

 much coarser than abactinally and there is no obvious distinction 

 between the marginal and central granules; even the largest plates 

 have only 20-25 altogether. The series adjoining the adambulacrals 

 extends out to about the sixth or seventh inferomarginal from the 

 tip; the next series reaches only to the ninth. At the middle of 

 each interradial margin there are about 3'< 2 actinolateral plates 

 abutting on each inferomarginal. 



Adambulacral plates 40-45 on each side (in the holotype) wider 

 than long at first but becoming squarish distally. The armature 

 consists of a furrow series of 4, blunt, thick, somewhat prismatic or 

 slightly flattened, subequal spines about 1-5 mm. long; back of these 

 is a nearly parallel series of 3 similar but shorter spines and the 

 outer end of the plate is occupied by 2-4 still smaller, but yet some- 

 what similar spinelets; these last are distinctly larger than the 

 biggest granules of the adjoining actinolateral plates. Oral plates 

 large but flat and not at all swollen ; the armature is almost exactly 

 similar to that of the adjoining adambulacrals; there are about 8 

 large spines on each free margin and a series of about 8 prismatic 



