104 s. goto: 



calcareous rods between the specimens from the Japan Sea and those 

 from the Pacific side, but they are of too trifling a character to be 

 made a basis for specific distinction, and my Pacific specimens are too 

 few. The superomarginal plates show very little on the abactinal 

 side, especially in the interbrachial arcs, where only the spines at 

 the aboral end are visible, but further out in the arms the plates 

 show distinct faces on this side. The keel of the superomarginal 

 plates become relatively broader towards the apex of the arms. 



Inferomarginals. — The inferomarginal plates are strictly coin- 

 cident with the superomarginals and are nearly triangular in 

 surface view in the interbrachial arcs. Further out in the arms 

 the plates are more or less rectangular ; and when viewed from 

 the interior of the body all the plates are either rectangular or 

 nearly square. The portion visible from the surface is the keel, 

 which is articulated with that of the corresponding superomarginal. 

 The individual plates of the inferomarginal series become distinct 

 from the superomarginal and the ventrolateral plates only after 

 maceration or treatment with caustic potash, and it is then seen that 

 the outer surface of each inferomarginal plate is curved and that the 

 sharply pointed, somewhat flattened actinolateral spine is twice as 

 far removed from the actinal end of the plate as from the abactinal. 

 The surface of the plate on the actinal side of the spine slants oblique- 

 ly towards the oral surface, while the part lying on the other 

 side stands up vertically towards the superomarginal. The margins 

 of the inferomarginals facing the fasciolar grooves are armed 

 with a row of 9-11 subcapillary spinelets similar to those of the 

 superomarginal series and connected together by a skin fold. Of 

 these spinelets those that lie on the abactinal side of the external 

 spine are similar in shape to those of the corresponding series of 



