118 s. GOTO : 



hexagonal form. These plates are broader than long, and arranged in regular 

 series of single cohinms extending from the margin of the disk to the 

 ambulacral fm-roAv. Their breadth diminishes someAvhat as they ax^proach the 

 margin, and consequontly that of the columns also. The adambulacral plates 

 join up to the infero-marginal plates along the whole length of the free 

 poiiiou of the ray, and there is consequently no extension of the interradial 

 area along the ray. The imbricating plates bear a few widely spaced mihary 

 tubercles or large granules upon their surface, usually four or five to the plate, 

 upon which, however, they have no definite arrangement. 



" Colour in alcohol, grey ; the paxillar area being a much darker shade, 

 which shows a strong contrast with the greyish white of the marginal plates. 



*' Yoking phase.' — There is a small example of this species, which, though 

 measuring only II = 10 mm., r=5mm., so closely resembles in all respects 

 tlie characters of the adult, that there is not the slightest hesitation in 

 determining it specifically. Beyond the fact that the rays are shoi*ter, the 

 terminal plate more tubercular and broader, and that a less number of 

 supero-margiual plates on the two sides of a ray meet in the median radial 

 line, I can scarcely detect a feature worth}' of mention as differentiating the 

 immature from the adult form ; excepting the changes in size, proportion, and 

 number wliicli affect plates and appendages normall}'. There are five su]_)ero- 

 marginal plates between the median interradial line and the terminal in the 

 small specimen. 



" Locality. — Station 237. Off Japan, south of Kawatsu. June 17, 1875. 

 Lat. 34° 37' 0" N., long. 140° 32' 0" E. Depth 1875 fatlioms. Blue mud. 

 Bottom temperatiu-e 35.°3 Fabr.; surface temperature 73.°0 Fal)r. 



" licnmrJis.- — HypJialaskr incrmis is distinguished from the other species 

 with seven cribriform organs by its robust and rigid body-frame, by the 

 supero-marginal plates meeting in the median radial line, by these being 

 devoid of spinelets, by the full}' developed paxilhe, and by the narrow 

 cribriform organ." 



