136 ART. 2. — H. MATSUMOTO : 



papillae absent. Arms also covered by a cereous skin. Dorsal 

 arm plates entire. Arm spines conical, blunt, stout, opaque. A 

 single conical, blunt tentacle scale to each pore. 



This new genus includes Ophiolebes tylota Clark, 1911, 0. 



jMchybactra Claek, 1911, Ophiactis clavigera Ljungman, 1866 



(referred to Ophiolebes by Lyman, 1882), Ophiacantha œdidisca 



Clark, 1911, Ophiolebes cUaphora Clark, 1911, 0. paucispina Clark, 



1911, and 0. brevispina Clark, 1911, the first being the genotype. 



Ophiosemnotes differs from the genuine Ophiolebes chiefly in 

 the short, rounded or triangular, exposed radial shields and in the 

 entire dorsal arm plates. In Ophiolebes as here restricted, the 

 radial shields are long, narrow, bar-like and not exposed, and the 

 dorsal arm plates are divided into two, inner and outer, secondary 

 plates. Ophiosemnotes is very near to Ophiochondrella, but differs 

 from it in the short ventral arm plates, which are separated from 

 one another, and in the single thick, not leaf-like tentacle scale 

 to each pore. In Ophiochondrella the ventral arm plates are 

 quadrangular, as long as the corresponding arm joint and joined to 

 one another, and the tentacle pores are provided with two thin, 

 leaf-like scales. 



Key to Japanese species of Ophiosemnotes. 



A — Disk closely covered with fine granules ; radial shields oval, 

 separated from each other ; dorsa] arm plates rather large, in 

 contact with each other in the free basal arm joints, bearing a row 

 of granules along the outer border ; arm spines rather short, upper 

 ones being nearly as long as the corresponding arm joint ; lower 



arm spines not clavate œdidisca. 



A A — Disk sparsely bessst Avith clavate tubercles and granules ; radial 



