130 ART. 2. — H. MATSÜMOTO : 



The present genus includes Ophiomltra exigua Lyman, 1879 

 (referred to Ophiothamnus by Verrill, 1899), Ophiothamnus Icevis 

 LtJTKEN & MoRTENSEN, 1899, and Ophiothamnus stultus Kœhler, 

 1904, besides the genotype, Ophiomltra dicycla Clark, 1911. 



Ophiurothamnus is very near to Ophiomi/tis and Ophtojjliuthaca, 

 but differs from the former chiefly in the very small dorsal arm 

 plates and in the basal arm spines approximating dorsally ; from 

 the latter in the absence of the marginal disk scales, in the smaller 

 interbrachial ventral surfaces, which are covered with fewer, 

 coarser scales, in the smaller dorsal arm plates, and in the basal 

 arm spines approximating dorsally. Further, this genus differs 

 from Ophiothamnus in the coarser disk scales, in the radial shields 

 being joined along the whole length, in the fewer and coarser 

 scales of the interbrachial ventral surface, in the well developed 

 genital bursae, in the stout oral shields, which are in contact with 

 the first lateral arm plates, in the stouter arms, in the very wide 

 ventral arm plates, which are as wide as the corresponding arm 

 joints, in the serrate arm spines, and in the usually hook-shaped 

 lowest spines in the distal arm joints. 



OphiurotJiamnus dicyclus (Clark). 



Ophiomltra dicycla : Clark, Bull. U. S. Nat. Mas., LXXV, 1911, p. 

 181, fig. 82. 



Eastern Sea ; 434 fathoms (Clark). Bungo Channel ; 437 

 fathoms (Clark). 



OpJiiopHntJtaca cardiomorpha (Clark). 



Ophiomltra cardiomorplia : Clark, Bull. U. S. Nat. Mus., LXXV, 1911, 

 p. 179, fig. 81. 



