MONOGRAPH OF JAPANESE OPHIUEOIDEA. 305 



and one articular pit at the enter end to fit to the t^vo condyles 

 and one pit of the radial shield. The genital scales are long, 

 wide, thin, leaf-hke, L-shaped in transverse section, articulating 

 with the genital plate near the outer end of the latter. The 

 radial shields in internal view are very large and completely 

 joined in pairs. Ophiojjœpale goèsiana Ljungman and Ophiermis 

 valUncola Lïman, which were dissected by Lyman, appear to be 

 essentially similar to the preceding in the internal structures, save 

 that the peristomial plates of the first are not triple but double, and 

 those of the second single for each oral angle. Again, according 

 to Lyman, the peristomial plates of Ophiopyren Jongispiniis liiiviAN 

 are double and very long, forming together a complete ring around 

 the mouth. As a wiiole, the internal structures of the present 

 family resemble those of OpMura and its allies. 



Key to Japanese genera of Ophioleiicidœ, 



A — Tentacle pores small^ each provided with a single scale. 



a — Oral papillse not soldered together, uniform in size, or the outer- 

 most one is larger than the others ; arm joints short ; dorsal arm 

 plates well developed, widely in contact with one another ; arm 

 spines uniform in length Ophioleiice. 



au — Oral papillœ soldered together, except the outermost two, which are 

 exceedingly large ; dorsal arm plates very rudimentär}', exceedingly 



minute ; basal arm spines especially long, the others short 



OpMotrocIms. 



^^— Tentacle pores large, each provided with two scales ; dorsal arm 

 plates very well developed ; ventral plates entire, in contact with one 

 another ; arm spines uniform in length Ophiernus. 



