JAPANESE ASTEEOIDEA. 345 



terradial line but become gradually smaller towards the tip of the 

 arms. Again, in the interbrachial angles the plates gradually 

 slant down towards the margin of the disk, so that one can not 

 conveniently distinguish the lateral and abactinal surfaces ; but 

 as the plates approach the tip of the arms the lateral face be- 

 comes more distinct. The surface of the plates is decidedly convex. 

 Each plate is bordered along its margin by a single series of small 

 rounded or cubical granules, of which those facing the infero- 

 marginals are frequently larger and irregular in arrangement ; the 

 whole remaining surface of the plates is entirely naked and 

 smooth (PL XIII, fig. 207). 



Inferomarginals. — The inferomarginals are thinner and less 

 convex than the superomarginals, and the plates are on a level 

 with the general actinal surface of the body. On either side of 

 the interradial line the plates are moderately thick ; they then 

 become thinner but again thicker toward the tip of the arms. 

 The marginal granules of the outer border of the plates are larger 

 than the others and are frequently arranged in two alternate rows ; 

 those of the other borders are similar to one another and to the 

 corresponding granules of the superomarginals (PL XIII, fig. 208). 



Adambulacrals. — The adambulacral plates are almost square 

 in form and the first one or two plates may bear each a trans- 

 versely elongated, valvate pedicellaria similar to those of the 

 ventrolateral plates described below. One or two plates further 

 out from the mouth may also bear a pedicellaria. The adam- 

 bulacral armature consists of two large spines on the furrow 

 margin, and 4 or 5 (exceptionally more) granules on the actinal 

 surface of the plate, the latter mostly in two rows (PL XIII, fig. 

 206). The furrow spines are large and the adcentral one is 



