34 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



proximally, usually becoming two distally; ampullae when deflated with two lobes; 

 gonads two to a ray, attached a little distance from interradial angle on level with 

 marginal plates. 



KEY TO THE SPECIES AND SUBSPECIES OF ZOROASTER HEREIN DESCRIBED 



a' With four series of actinolateral plates on proximal part of ray; dorsolateral and intermarginal 

 papular areas very small with normally one papula each; inferomarginal and actinolateral 

 spines slender, closely appressed. ;•! 



b> Supermarginal spines very slender, appressed; no adradial spines; 10 carina plates cor- 

 respond to 14 adradial and 14 superomarginal plates; fourth or lowest actinolateral series 

 extending far along ray; plates of first two actinolateral series as broad as mferornar- 



ginals; adradial plates broadly overlapped by adjacent series ophiurus Fisher 



o> Superomarginal spines more robust, often bristling; an incomplete series of adradial spines; 

 10 carinal plates correspond to 19 adradial and 19 superomarginal plates; fourth or 

 lowest actinolateral series short (one-sixth length of ray); plates of first actinolateral 

 series, only, as broad as the inferomarginals; adradial plates exposed (about 50 per cent 



broader) actinocles Fisher. 



o». With three series of actinolateral plates; the two dorsolateral and the intermarginal series of 

 papular areas with two to four papulae, the areas rather large; all spines rather long and 

 bristling. 

 V. No large pedicellaria regularly on the second spine of prominent adambulacral plates 



evermanni Fisher. 



V. A large pedicellaria regularly present on the second spine of prominent adambulacral plates 

 mordax Fisher. 



ZOROASTER OPHIURUS Fisher 



Plate 13, Figures 1, la-le; Plate 17; Plate 18, Figures 2, 3 



Zoroaster ophiurus Fisher, Bull. Bureau Fisheries, 1904, vol. 24, June 10, 1905, p. 315; Ann. 

 and Mag. Nat. Hist., ser. 9, vol. 3, 1919, p. 390.— H. L. Clark, Bull Amer. Mus. Nat. 

 Hist., vol. 32, art. 8, July 9, 1913, p. 199; vol. 48, art. 6, 1923, p. 152; Mem. Mus. Comp. 

 Zool., vol. 39, No. 3, 1920, p. 102. 



Diagnosis. — Belonging to the slender-rayed relatively delicate carinatus group. 

 Rays five. R 140 mm.; r 10mm.;R = 14r. Breadth of ray at base, 11 mm. Disk 

 small and convex; rays very long and slender, tapering from a narrow base to an 

 attenuate extremity. Abactinal surface of rays strongly convex, with a fairly promi- 

 nent median radial ridge. Adradial plates sunken, rather inconspicuous, nearly 

 covered by adjacent series; four series of actinolateral plates; marginals and actino- 

 laterals each with a veiy slender needle-like spine; numerous prominent pedicellariae; 

 miliary spinelets slender, curved, spaced, not so long on rays as the pedicellariae; 

 carinal plates with a short blunt, subtruncate tubercular spine, much heavier than 

 the lateral spines and usually more or less grooved or scored at the end. 



Description. — Plates of abactinal surface of disk rather convex, the primary 

 radials and basals being most prominent. They are covered with delicate and slender 

 sharp spinelets, about 1 mm. in length, distinctly spaced, among which are scattered 

 numerous straight pedicellariae, larger than the spinelets, and, of course, much more 

 robust. The median radial seriss of plates is more prominent than the rest, and 

 each bears, on a central prominence, a thimble-shaped tubercle. The abactinal and 

 lateral faces of the ray are gradually confluent by a well-rounded margin, the supero- 

 marginal plates not being prominent in any way. Between the superomarginal and 

 adambulacral plates are five longitudinal series of exactly similar plates — an infero- 



