The Echinoderm Fauna of South Africa. 2'i7 



R = 2'65r and 2-5 br. In the largest specimen, R = 78 mm., r = 26 

 and 6r = 28; thus R = 3r and '2-78 hr. It is thus obvious that the 

 larger the specimen of this species, the longer and proportionately 

 narrower are the rays. The number of supermarginal plates on 

 each side of a ray in these four specimens is 1C), 22, 28 and 39 

 respectively. The number of marginals is relatively greater there- 

 fore in proportion to the length of the ray in young specimens than 

 in adults; thus, while the length of ray increases five times tin* 

 number of marginals is increased only two and a half times. It will 

 be noticed that the largest African specimen has several more supero- 

 marginal plates than much larger specimens of sladeni and laetmophilus, 

 but I think this is merely a matter of individual, or possibly, geo- 

 graphical variation. 



In the smallest specimen, the enlarged spinules on the outer ends 

 of the inferomarginal plates are barely recognizable and then only 

 in the interbrachial arcs. They are more pronounced but are not 

 at all conspicuous in the specimen with R = 26 mm. The adambu- 

 lacral armature shows very little change with growth; in the smallest 

 specimen there are 5 and often 6 adarnbulacral spines and they are 

 somewhat compressed, especially near base; in the largest specimen, 

 there are 7, occasionally 8, adambulacral spines and they are mar- 

 kedly compressed at base. 



Colour in life: upper surface reddish orange, lower surface pale. 



P.F. 2285. Lion's Head, Cape Town, N. 67 E., 25 miles. 131-136 

 fms. Black specks. 2 specimens; adult. 



P.F. 2330. Same station. 2 specimens; young. 



P.F. 2798. Vasco de Gania Peak, N. 71 E., 18 miles. 230 fms. 

 St. 1 specimen ; adult. 



P.F. 17604. Cape Point, E. by N., 30 miles. 345 fms. Green sand 

 and mud. 4 specimens; very young. 



BATHYBIASTER ROBUSTUS. 



Archaster robustus Yerrill, 1884. Amer. Journ. Sci. (3), vol. 28, p. 383. 

 Bathybiaster robustus Verrill, 1894. Proc. U. S. Nat. Mus., vol. 17, p. 256. 



These specimens range in size from R 7 mm. to R = 80mm. 

 The largest has been critically compared with similar specimens of 

 robustus from off the Eastern coast of the United States and there 

 is no doubt of their identity. The growth changes of this species 

 are very interesting. Small individuals were described by Sladen 

 (1889, CHALLENGER Ast., p. 236, pi. 40, figs. 3-6) as Phoxaster pumilus, 

 supposedly representing a new genus, distinguished from Bathybiaster 



