204 s. goto: 



other superomarginals. The entire external surface of the suparo- 

 marginal plates is thickly covered with very slender, almost sub- 

 capillary, pointed, conical spinelets, which are coarser aronnd the 

 base of the conspicuous spines. The transverse grooves between 

 the successive superomarginals are absent. The plates in the 

 interbrachial angles are very high, facing towards the outside and 

 presenting a small surface on the abactinal side ; but as they 

 proceed further into the arms, the plates become more and more 

 horizontal and nearly the whole of their surface is turned 

 towards the abactinal side. At about the middle of the arms 

 the plate is nearly one-half wider than long. Except in the 

 interbrachial angles where the superior and inferior marginals 

 stand flush, the lateral margin of the arms is formed by the 

 inferior series. 



Infer omarginaU. — The most striking feature of the infero- 

 marginals is an obliquely transverse series of large, very slightly 

 flattened spines, mostly four or five but occasionally six in 

 number. Aside from occasional irregularities, the innermost three 

 spines usually form a strictly transverse series near the abcentral 

 margin of the plate, and the rest an oblique series running towards 

 the outside and centre. The two portions sometimes make an 

 angle, but usually they are continuous and pass gradually the one 

 into the other. The spines generally increase in length outwards, 

 but the most external one may be shorter than the next. The 

 longest spine may measure as much as 9 mm. or a little more. 

 The surface of each inferomarginal plate may be distinguished 

 into two sections which are covered with different spines. The 

 abcentral two -third s or a little more of the surface, to which the 

 series of conspicuous spines belongs, is covered with well-spaced, 



