112 s. goto: 



" The mouth-i^lates are rather large, forming an acute angle adorallj, 

 with an elevated angular ridge along the hne of the suture, each plate be- 

 ing sti'onglj bent downwards, and having the uptm-ned edges compressed 

 together to form the keel. The aboral extremity is more elevated tlian any 

 other pai-t, and presents a sharp angular -peak, the mouth-plates sloping 

 down therefrom with a graceful inward cm've to tlie level of the actinal 

 intenvadial area. Their armatm-e consists of a single short conical mouth- 

 spine, placed at the extremity of the adorai j)eak ; and two others, about 

 equal in size to the spinelets of the adambulacral armatm-e, stand on the 

 lateral margins of each plate, the most adorai of the two being situated 

 nearly midway between the extremities of the margin. 



" The actinal inteiTadial areas, wliich are small and sagittiform in out- 

 line, do not extend beyond the tliird adambulacral plate. The intermediate 

 plates are small and subregular, transversely elongate on the outer part of the 

 area, and with a tendency to imbricate ; tliis character, however, being so faintl}' 

 presented that it is difficult to say whether imbrication really exists or not. 



"Colom- in alcohol, greyish white generally, but darker over the abacti- 

 nal area of the disk. 



"Locality. — Station 237. Oif the coast of Japan, south of Ivawatsu. 

 June 17, 1875. Lat. 34° 37' 0" N., long. 140° 32' 0" E. Depth 1875 fathoms. 

 Blue mud. Bottom temperatm-e 35.°3 Fahr. ; sm-face temperature 73.°0 Fahr. 



" Remaries. — Porcellanaster tuherosvs is distinguished from the other 

 si)ecies of Porcellanaster with only one cribriform organ in each iuterbrachial 

 arc, by its broad and robust rays, with a large and tubercular terminal 

 plate armed with tlu-ee spines, and by having only two supero-marginal 

 X3lates on each side of a ray armed with spines, which are stout. Other 

 points of difference are noticed in the description." 



Hjjphalaster inennis Sladen. 



Tliis species is not represented in any of the collections mentioned at 

 the begiiming of this x)aper. Its first description by Sladen is as foUows 

 ['83, p. 239 ] : 



