JAPANESE ASTEßOIDEA. 109 



" Tlie marginal plates form a deep margin and cm:Te over romidly in 

 the interbracLial angles, tlie inferior as well as the superior series being 

 visible from above. Upon the rays the superior series arch well over and 

 almost meet in the median dorsal line, giving to the ray a more or less 

 subcarinate character. The supero-marginal x^lates are four in number from 

 the median interbrachial line to the extremity, exclusive of the large terminal 

 plate, and all are distinctly longer than liigh. The second and tliird supero- 

 marginal plates from the interbrachial line bear shoii; conical upright spine- 

 lets ; but all the rest are unarmed excepting the terminal j)late, which 

 carries tlu*ee spines — one at the exti'emity in the median line of the ray, 

 and one on either side at the anterior extremity of the inferior margin of 

 the plate. The terminal plate is swollen and prominently tubercular dorsal- 

 ly, and is excavated on its outer extremity for the passage of the terminal 

 ambulacral tube. In one ray of the specimen under notice, the penultimate 

 supero-marginal plates are also swollen and ankylosed, in such a manner as 

 to resemble the terminal plata, and bear a single s^^inelet. The infero- 

 marginal plates are five in number, and are much shallower than the 

 superior series and also shorter. The two series consequently do not cor- 

 respond, a result probably brought about by the extreme develojoment of the 

 terminal plate, which occupies the sj)ace both of superior and inferior plate. 

 Cribriform organs one in each angle, rather broad and with a deep depres- 

 sion down the median line ; sti'ucturè lamelliform. 



"Ambulacral furrows wide and open, occupying nearly the whole of the 

 actinal surface of the ray. Adambulacral plates small, and form regular 

 triangular prominences which indent, as it were, the margins of the fmTOW. 

 Ambulacral spines two on each plate, short, subconical, sharply point^ed or 

 thorn-like, placed side by side on the aboral side of the x^i'ojecting angle ; 

 they are consequently directed aborally and at an angle towards the fm-row, 

 diverging also slightly from one another. 



" Mouth- j)lates rather large, forming an acute angle adoralh', with 

 an elevated angular ridge along the Hue of sutm-e, each plate being strongly 

 bent downwards and having the uptm-ned edges compressed together to 

 form the keel. The aboral extremit}- is more elevated than any other part 



