MONOGKAPH OF JAPANESE OPHIUROIDEA. 287 



and stout, irregularly triangular, longer than wide, longer without 

 than within ; those of a pair separated from each other by the 

 large second radial, small third radial and the small first dorsal 

 arm plate. Interbrachial ventral surfaces covered chiefly by the 

 very large, stout genital scales and a very large, stout, convex 

 plate, lying directly outside the oral shield. Genital slits small, 

 very short and narrow. 



Oral shields large, pentagonal, with very long inner and very 

 short lateral sides, an acute inner and rounded outer angles, stout, 

 longer than wide, wider without than within. Adorai shields very 

 large, stout, long, wide, tapered inwards, meeting with each other. 

 Seven or eight oral papillas on either side, squarish, flat, soldered 

 together, and obscuring the original number ; the outermost one 

 is exceedingly large and wide, and arises from the adorai shield ; 

 the next is much smaller and narrower than the preceding, but 

 distinctly larger and wider than the following. Three teeth, small, 

 triangular, pointed. 



Arms cylindrical, gradually tapered. First dorsal arm plate 

 very small, rounded triangular, convex, wedged in between the 

 radial shields. The next is also small, quadrangular, with rounded 

 angles and convex sides, wider than long, with convex surface, 

 in contact with the first. The five or six remaining are small and 

 triangular, with rounded angles and convex sides and surface, and 

 diminish in size outwards. Lateral arm plates well developed, 

 covering almost the entire surface of the arms, convex, flared. 

 Only three ventral arm plates : the first small, pentagonal, wedged 

 in between the adorai shields ; the second and third also small, but 

 a little larger than the first, pentagonal, with the tentacle pores 

 at the lateral angles. Only two pairs of tentacle pores and 

 scales ; the latter small and oval, the first scales being larger than 



