MONOGEAPH Or JAPANESE OPHIUROIDEA. 253 



in the relatively larger radiais, in the fewer and smaller intervening 

 scales, in the shape of the first, as well as second, interradials, in 

 the shape of the first ventral arm plate, in the ventral arm plates 

 diminishing in size more rapidly outwards, and in the larger arm 

 spines. 



Aspidophiura forbesi (Duncan). 



OpMoglypha forbesi : Duncan, Journ. Linn. Soc. London, XIV, 1879, 

 p. 449, PI. IX, figs. 1-3 ; Lyman, Rep. Challenger, V, 1882, p. 77 ; Kœhlei;, 

 Bull. Sei. Fr. Belg., XXXI, 1898, p. 63 ; Kœhlee, Res. Exp. Siboga, XLV, 

 Pfc. 2, 1905, p. 22. 



OpJimra glyptodisca : Clark, Bull. U. S. Nat. Mus., LXXY, 1911, p. 

 91, fig. 31. • 



Korean Sea; 51-59 fathoms (Duncan, Clark). 



Indian Ocean and Malaysian waters. 



Comparing Duncan's and Clark's descriptions and figures, I 

 can not find any tangible characters, by which Clark's species 

 is distinguished from Duncan's. I therefore look upon the latter 

 as a synonym of the former. The difference in the number of 

 secondary disk scales, which is the only one I can recognise, 

 appears to me to be due merely to the fact, that Clark's type is 

 slightly larger than Duncan's. 



Stegophiura Matsumoto, 1915. 



Disk high and arched, covered with thick plates or scales, 

 among which the primaries are conspicuous. Radial sliields stout, 

 more or less joined in pairs. Genital papilla) and arm combs well 

 developed ; papilla) of the latter long, usually spiniform. Oral 

 sliields large, oval or pyriform. Arms very short, stout, higher 



