J.yANESE ASTEEOIDEA. 465 



more or loss concealed from view ; there are two or two and a 

 half of them corresponding to one inferomarginal plate in the 

 greater part of the arms. The armature consists of two rows of 

 spines, an inner of smaller spines, mostly six in number, arranged 

 like the fingers of the human hand, the middle ones longer than 

 those towards the ends, and an outer of much stouter, prismatic 

 spines, mostly two but sometimes three in number, of subequal 

 length, and with apices either irregularly blunt or in the form of 

 a wedge. When there are only two of these outer spines, there is 

 usually a very short, granuliform spine at the adcentral end of 

 the plate. At the same end of each plate, between the two rows 

 of spines there is a tolerably large, forcipiform pedicellaria. 



The foregoing description applies to the adambulacral plates 

 near the mouth, but those which lie some distance away from it 

 have mostly an additional row of five or six granules on the outer 

 side of the outer row of spines, just as in 0. modestus. 



Mouth- plates. — The mouth-plates themselves can not be observ- 

 ed from the outside ; the armature consists of two rows. The 

 inner consists of nine stout spines, of which the last five or six 

 at the abcentral end are slightly smaller than the otbers, and the 

 one at the mouth end has usually the form of a triangular prism. 

 The outer row consists of four spines, similar in form and sube- 

 qual in length to the adcentral spines of the inner row. The 

 two rows of oral spines for each pair of mouth -plates have the 

 form of a V telescoped into another V. 



Ventrolaterals. — The ventrolateral plates are completely cloth- 

 ed over with coarse, flattened, polygonal granules, and are more 

 distinct than in 0. noclosus, but less so than in 0. moedstus. 

 Generally speaking the plates are larger and more regular in the 



