The Echinoderm Fauna of South Africa. 245 



in this species. The smallest specimen (R = 6 mm.) has R = 1-5 r 

 and is thus somewhat pentagonal with deeply concave sides; the 

 pseudopaxillae are similar to those of the adult and the madreporite 

 is completely concealed ; there are 8 marginal plates in each series, 

 on each side of a ray and they are quite uniformly covered with 

 minute rough spinules; the actinal interradial plates are few and 

 covered like the marginals. In two particulars this youngster is 

 quite different from the adult; the large spines and spinelets of the 

 adambulacral and marginal plates are wanting and there are distinct, 

 though simple, pedicellariae on the abactinal surface and between 

 the marginal plates, as well as actinally. On the most interradial 

 of the inferomarginals, one spinule is distinctly larger than the others 

 and may be considered the first indication of the spine, later so 

 prominent. The terminal plate of each ray is relatively very large; 

 on each side of the tip. near the oral surface is a large spinelet 

 and back of this (orally) are two smaller spinelets. 



The next larger specimens have R = 7'5 mm., r = 3 - 5; hence 

 R = 2-lr. The spinulation of these individuals is exactly like that 

 of the smallest, except that on some of the distal adambulacral plates, 

 one of the actinal spinelets is noticeably bigger than the others ; 

 pedicellariae are very noticeable, especially among the marginal plates. 

 A specimen with R 10 mm. is not essentially different in any 

 way. A specimen with R = 12-5 mm. and r = 4'5mm. (R = 2-75 r) 

 has the large spinelet indicated on most of the inferomarginal plates, 

 quite distinct on nearly all the adambulacrals, and evident on the 

 interradial superomargmals; there are no pedicellariae except on the 

 actinal interradial areas. A specimen from the same station as this 

 one, with R = 13 mm. and r = 5'5 mm. (R = 2'37 r) has distinctly 

 wider rays and there are many pedicellariae, chiefly of two spinelets, 

 all over the abactinal surface ; large spinelets are indicated only on 

 the interradial inferomarginals and doubtfully on a few distal adam- 

 bulacrals. The largest of the young individuals, from the same 

 station as the holotype, has R = 19 mm. and r = 7 ; R = 2'7r; 

 there are no pedicellariae, the large spinelets of the inferomarginals 

 are conspicuous while those of the superomarginals are evident; the 

 proximal adambulacrals show no large actinal spinelet but on all of 

 those on the distal half of the arm it is perfectly distinct. The adult 

 specimen from 16743 has R = 48 mm., r= 14 and hence R = 3'5r 

 but in only one other particular does it show any notable difference 

 from the holotype ; there is no second large spinelet on any margi- 

 nal plate. 



To sum up the growth changes of this species then we may say 



