JAPANESE ASTEROroEA. 



215 



FersepJionaster triacanthus, n. sp. 



(PL n, figs. 14-22). 



This species presents a very strong external resemblance to 

 Astropecten, to which genns it will be referred by any casual 

 observer ; but the presence of the anus, together with a few other 

 points of less importance, exclude it from that genus. The anus 

 is very difficult to recognize, but dissection established its presence 

 beyond doubt, and in certain favourable cases, when the speci- 

 mens are dried, the anus can be recognized externally as a very 

 small opening in the centre of a conspicuous conical prominence, 

 where the paxillae are considerably smaller than in the surrounding 

 parts. I have four specimens of this species, all from the same 

 part of the sea, and from nearly the same depth. This species is 

 so closely related to the starfish described by Sladen from the 

 same region under the name of Astropecten hrevispinus, that I 

 should not wonder if a study of a large number of specimens 

 should lead to an amalgamation of the two species. In any case I 

 have no doubt that Astropecten hrevispinus Sladen should be referred 

 to the genus Fersephonaster. I shall come back to this question later. 



The measurements of the four specimens are as follows : 



