JAPANESE ASÏEROIDEA. 51 



surface. They are smaller in size, and are usually formed by 

 spines belonging to three paxillao, there being three or four spines 

 to each paxilla. They may also be formed by spines belonging 

 to only two paxillas. 



Madreporite. — The madreporite is fairly large, rounded poly- 

 gonal in outline, elevated above the general surface of the 

 abactinal side, close to the margin of the disk ; the grooves are 

 mostly radiating. 



Locality. — My specimen is from Yodomi, off Misald, from a 

 depth of 160 m. The colour of the dried specimen is brownish 

 yellow all over, except the central perianal area w^hich is orange 

 red. 



A single dried specimen in S.C. 



This species is closely relatad to Ch. oxijacanthus (Sladen), 

 but is distinguished from it by several characters. 



Dr. W. K. Fisher points out to me that this species perhaps 

 belongs to Luidiaster, in which special dorsal muscles are attached 

 to either one or two of the proximal ambulacral plates by a 

 distinct tendon, while in Cheiraster they are not. This and the 

 allied genera have recently been subjected to revision by Ludwig 

 [: 10], and according to his synoptical key the present species 

 appears to fall in well with the genus Luidiaster as defined by 

 him. Although owing to the dried condition of my only specimen 

 I am not able to settle the anatomical characteristic mentioned 

 by Fisher, there is no doubt that the present species stands close 

 to Ch. oxyacanthus ; and as the latter is referred to Luidiaster by 

 Ludwig yodomiensis may perhaps also be included in that genus. 



