JAPANESE ASTEBOIDEA. 245 



mediate plates. Foiu' spinelets commonly occm* in tlie inner actinal series 

 and about tlu'ee to five in each of the outer ; or the two latter series may 

 be wanting, the spinelets, instead, forming an irregiilar group, especially on 

 outer part of ray where there are frequently upward to sixteen or twenty 

 actinal spinelets. 



" Mouth ]3lates narrow, rather prominent actinally, the free margins of 

 the combined plates forming a salient angle into actinostome ; free margin 

 of each plate shghtly angular near inner end and longer than the margin 

 adjacent to first adambulacral. Armature consists of a fm-row series of about 

 six or seven taj^ering spinules decreasing in length from the inner enlarged 

 tooth, outward, and thence continued along margin adjacent to first adambu- 

 lacral in about nine nmch smaller spinelets similar to those of actinal in- 

 termediate plates. A superficial series of similar spinelets follows margin of 

 median suture, increasing in size toward inner angle of plate, and an in- 

 complete more or less irregular series often, but not always, occm'S between 

 marginal and superficial series. There is more or less variation in the details 

 of dental armatm'e. The exposed, outer, shghtly convex surface of the com- 

 bined plates has the appearance of being covered with a bristling armatm'e 

 of shoi-t papiUiform spinelets, very similar to those on adjacent actinal inter- 

 mediate plates. 



" Madreporic body rather large, about midway between centre and 

 extreme edge of disk. Striations coarse, centrifugal, very irregular ; mad- 

 reporic body sometimes nearly hidden by five or six large paxillae. 



" Superambulacral plates present, though small. Absent from the first 

 ambiüacral plates, and from the distal six or seven, which are much re- 

 duced and crowded against the adjacent infero marginals. Gonads forming a 

 tuft of tubules on either side of the interradial septum, five or six tubules 

 (two or three times dichotomously divided) to each tuft. The gonads do not 

 consist of a series of tufts extending along the rays as in Dipsacaster. A 

 Polian vesicle in each interradius. InteiTadial septa iincalcified. 



" Variations. — The specimens assembled under this foim present a very 

 considerable amount of variation, and when the extremes are placed side by 

 side it is liard to believe tliat tliere are not two valid species. But there 



