1915.] NATURAL SCIENCES OF PHILADELPHIA. 47 



entire, very thick, fused with oral frames, which are very 

 stout; vertebriE rather short and very stout, many proximal 

 ones discoidal, none divided into halves; wings of vertebrae 

 almost equally thick laterally and dorsally; vertebral articu- 

 lations streptospondyline; articular peg very rudimentary, 

 or absent OPHiOBYRSiNiB. 



Subfamily 1. OPHIOMYXIN^ Ljungman, 1871 (emend.). 



(Characters as given above in key.) 



This subfamily includes Ophiohelus, Ophiosciasma, Ophiogeron, 

 Astrogeron, Ophiocynodus, Ophiostyracium, Ophiosyzygiis, Ophio- 

 leptoplax, Ophioscolex, Neoplax, Opkiomora, Ophiomyxa, Ophiodera, 

 Ophiohymen, and provisionally Ophiamhix, besides two new genera, 

 Ophiostiha and Ophiohyalus. 



OPHIOSTIBA gen. nov. 



Disk covered by a skin containing a number of scattered granules. 

 Radial shields very rudimentary, forming a continuous row with 

 the marginal disk scales, which are well developed, as in Ophiomyxa, 

 Ophiomora and Neoplax. Teeth and oral papillae present, with acute 

 ends. Arms skin-covered; dorsal arm plates absent, while the 

 lateral arm plates are subventral, so that the dorsal side of the arms 

 is largely naked. Distal vertebrae more or less divided into halves 

 by a longitudinally fusiform pore. Arm spines few, all converted 

 into compound hooks. Tentacle scales absent. 



This new genus differs from Ophioscolex chiefly in the presence of 

 the marginal disk scales and in the conversion of the arm spines 

 into compound hooks; and from Neoplax in the fewer arm spines, 

 which are converted into compound hooks, and in the absence of 

 tentacle scales. 

 Ophiostiba hidekiii sp. nov. 



Diameter of disk 3.5 mm. Length of arms 16 mm. Width of 

 arms at base 0.8 mm. Disk hexagonal, with concave interradial 

 borders, covered by a soft skin, which contains a number of scattered 

 granules. Radial shields very rudimentary and insignificant, 

 forming a continuous row with the marginal disk scales, which are 

 well developed. Genital slits very small and short. 



Oral shields rhomboidal, with perfectly rounded outer and lateral 

 angles, convex, slightly longer than wide; each serving as a madre- 



1 Dedicated to the memory of my friend, Hideki Chiba, who met with an 

 untimely death a few days after assisting me in dredging my material in the 

 Sagami Sea. 



