220 s. GOTO : 



slightly more outwards than midway between the margin and the 

 centre of the disk. The grooves are irregular (PL II, tig. 22). 



Terminal plate. — The terminal plate is rather large and 

 elongated, and bears three spines at the end. 



In a well preserved alcoholic specimen the colour is brownish 

 grey for the marginals, the same color of a darker shade for the 

 ventrolateral area, and the same colour of a lighter shade for the 

 aboral surface. The terminal parts of the arms and the adam- 

 bulacral portions are almost colourless. The papulae are short 

 conical processes of a deep brown colour, and are very numerous. 

 They are, however, absent from the central part of the disk and 

 a rather wide zone along the middle of the arms, exactly as in 

 Astropecten. 



Locality. — One of my specimens is from the Bay of Suruga, 

 at the entrance of Enoura Cove, depth 560 m.; the others are from 

 the Sagami Sea, depth 480 m. 



Four alcoholic specimens in S. C. 



In this species also the superambulacral plates are well 

 developed. 



Remarias. — As stated above this species is very closely related 

 to Persephonaster Itrevispinus (Sladen) mentioned below, with wliich 

 further study may possibly prove it to be identical. So far as 

 Sladen's description goes, there are, liowever, well marked though 

 not very great differences between the two species, which may be 

 enumerated as follows : 



Radial ratio 3.2 for P. hrevispinus (R=32mm., r = 10mm.) as 

 against 3.8-4.5 for P. triacanthus. 



The termhial slender portion of the arms present in P. 

 triacanthus is not found in P. hrevispinus. 



