MONOGRArH OP JAPANESE OrHIUROIDEA. 219 



^'— Disk, aud radial shields usually, closely beset with minute tubercles, 

 "without a network of white streaks ; dorsal arm plates free of trans- 

 verse white streaks. 

 g — Arms six to thirteen times as long as the disk diameter ; arm 



spines of free basal arm joints not exceedingly short. 

 h — Ai-ms seven to nine times as long as the disk diameter ; outer 



lateral angles of the dorsal arm plates perfectly rounded. 

 i — Arms about seven times as long as the disk diameter ; dorsal arm 

 plates less than twice as wide as long, with well defined inner 

 lateral angles and the lateral borders moderately divergent outwards ; 



middle arm spines clavate obhisa, 



ii — Arms about nine times as long as the disk diameter ; dorsal arm 

 plates more than twice as wide as long, with the lateral borders 

 very strongly divergent outwards, so that the inner and lateral 

 borders practically form one continuous curve ; arm spines not 

 clavate hirsuta. 



lih — Arms about thirteen times as long as the disk diameter ; dorsal 

 arm plates more than twice as wide as long, with the iuner and 

 outer lateral angles not rounded but sharp ; each plate with three 



white spots along the outer border ; arm spines not clavate 



puncloUmhata. 



gy — Arms about eighteen thnes as long as the disk diameter ; spines of 

 free basal and more internal arm joints exceedingly short ; dorsal 

 arm plates about twice or more than twice as wide as long, with 

 very well defined angles and borders longipeda. 



OpJiiofJtrix panchyendyta Clark. 



OpUothrix pancliyendyta : Clark, Bull. U.S. Nat. Mus., LXXV, 1911, 

 p. 264, fig. 131. 



Korea Strait ; 59 fathoms (Clark). 



