A. M Verrill — North American Ophhiroidea. 361 



Only a single species is known : OphiothoUa suppUcans Lyra., 

 taken off Juan Fernandez, in 1825 fathoms, Challenger Expedition. 



Family, OPHIOHELIDJE, nov. 



No radial shields. Disk-scales very thin or rudimentary. Arm- 

 bones divided into right and left plates. Oral papillae spiniform, 

 few, in a simple row. Teeth spiniform. Distal joints of arms bear 

 rows of peculiar grapel-like or "parasol-shaped" spinules, in place 

 of true spines. Only one genus is known. 



Ophiohelus umbella Lym. 



Mem. Boston Soc. Nat. Hist., 1880, pi. i, figs. 5-10 and 16. 



This, the type-species, was taken off Barbadoes, in 82 fathoms. 



O. pellucidus Lym. 



Op. cit., pi. i, figs. 11-15, 1880. 



This species was taken off the Fiji Islands, in 1350 fathoms. Chal- 

 lenger Expedition. 



Family, OPHIOMYXIDiE Ljung. (restr.), 1866. 



Ophioscolecidce (jiai^s) Lutk., 1869. 

 • Ophiomyxmce {svLh-tsivaily) Ljung., 1871. 

 Ophiomyxidcp, Carus, Faunae Medit., p. 96, 1884. Verrill, Oph. Bahama 

 Exped., p. 65, 1899. 



Disk and arms covered with thick cuticle, and usually with only 

 a row of marginal disk-scales, and a few scattered ones imbedded in 

 the cuticle, but visible only when dried. Radial shields small, 

 usually with a proximal series of small supplementary scales. 



Teeth and oral papillae stout, flat, with the end serrated. No 

 tooth-papillae. True tentacle-scales generally absent. Under arm- 

 plates small. Side arm-plates sub-ventral, bearing several rough 

 divergent spines. Upper arm-plates rudimentary or lacking ; when 

 present, comjDOsed of small pieces. Two large, triangular, peristo- 

 mial plates on each mouth-angle. 



Arm-bones peculiar, belonging to the modified " hour-glass- 

 shaped *' type, with well-formed condyles on both ends. 



Ophio'tnyxa and Ophiodera are the only genera described. The 

 second genus has the following characters : 



