648 



s. GOTO : 



which the convex ridges of the arms radiate, separated from each 

 other by tolerably distinct interradial farrows (Pl. X[X, fig, 279.) 

 The upper surface appears more or less rough, owing to the pre- 

 sence of plates which are larger and more prominent than the 

 surrounding ones and bear larger spines. In some specimens these 

 larger plates are very numerous, but in others they are few. 

 The interradial margin is well scooped out but not angular. The 

 papular pores are single and stop about two plates from the 

 superomarginals on the sides of the arms and four or five plates 

 from the same in the interradial lines. The radial ratios are 

 given below : 



The superomarginal plates are more distinct than in A. 

 hatheri, being larger than the adjoining plates, and bearing at the 

 interbracliial angle each (3-10 spines frequently arranged in two 

 rows along the length of the plate. The inferomarginals occupy 

 the very margin of the body and can be seen both from the 

 actinal and abactinal sides. Tlie spines of the abactinal side of 

 the plates are like those of the superomarginals, but slightly 



