108 s. goto: 



removed from the centre of the disk as from the margin, this 

 variation in position being largely due to the degree of inflation 

 of the dorsal body wall. The madreporite is either circular or 

 elhptical in outhne and covered with subparallel grooves showing 

 a tendency to converge towards the inner end of the plate (PI. 

 Vir, fig. 119; PL VIII, fig. 126). In some specimens there were 

 a few granules near the margin of the plate. 



Terminal plate. — The terminal plate of the arms is comparative- 

 ly large and conspicuous and nearly quadrangular in form. The 

 surface may be finely granulated and there are a pair of short 

 spines at the apex, which are apt to fall off. 



Locality. — Japan Sea ; Misaki. It occurs on fine mud, with 

 which its stomach is completely filled. 



Specimens in S. C. 



Porcellanaster tuherosus Sladen. 



Tills species is not represented in any of the collections on wliicli this 

 paper is based. The following is the first description of it [Sladen, '83, p. 223] : 



" Porcellanaster tuherosus, u. sp. 



" Rays five, interbracliial angles well rounded, the minor radial porjpor- 

 tion being 32 per cent., 11=18.5 miUim., r = 6 millim. The rays spring 

 gi'adnally from the angle and taper moderately towards the extremity, main- 

 taining a robust cliaracter tlnoughout. Disk not high, and very slightly 

 inflated. Dorsal area covered with a rather fleshy integument beset with 

 simple spinelets somewhat closely placed ; these are short, cyfindiical, obtuse ; 

 covered with membrane, and occupy the Avhole of the sm-face excepting only 

 the extreme angle at the base of the ray. A well-developed epiproctal tubular 

 prolongation rises from the centre of the dorsal area, and is nearly equal in 

 length to the distance between the centre and the innßr edge of the margi- 

 nal plates in the arm-angle ; it tapers very slightly towards its extremity 

 and is indm*ated with spicular spinelets like the rest of the dorsal membrane. 



