160 BULLETIN' 7(5, UNITED STATES NATIONAL MUSEUM 



lacral plates in contact inierradially, but a large specimen which I have (station 3548, 

 Bering Sen) has three pairs in contact. 



One of the best differences seems to be the compound structure of the papulae, 

 to which the finely papillose appearance of the, interspinal spaces is due. In Ste- 



asterias the papulae are simple papillae, not at all subdivided. 



. 1 ji/ii /listerias japonica superficially resembles Aphanasterias pycnopodia but its 

 inys are stouter. Its spinelets are more like those of Stcphanasterias. There are 

 l hue or four inferomarginal, and the same number of superomarginal spines in ver- 

 tical (transverse) combs, the abactinal spinelets are in small groups, and the papulae 

 are simple. The straight pedicellariae are inconspicuous and lanceolate, and the 

 crossed pedicellariae are quite small (0.16 to 0.18 mm. long; pi. 72, fig. 5). As in 

 AphtiiHixtt /in* the adambulacral plates are regularly diplacanthid, the ambulacrals 

 are much compressed, and the adoral carina is narrow and in large specimens com- 

 posed of three to five pairs of plates. But the resemblance of this feature to that of 

 Aphanasterias pycnopodia is not strong, since the carina is much more constricted in 

 Aphelasterias and the first and second adambjilacrals are longer than the succeeding. 



In Stephanasterias the gonads open at the base of the ray, between the supero- 

 marginal and inferomarginal plates; in Aphelasterias they are attached to the inner 

 surface of the superomarginals a short distance from the base of the ray (a trifle less 

 than r), but the ducts open just above the superomarginals. In the present genus the 

 1 1 chment point is close to the interbrachial angle, above the superomarginals (which 

 turn upward rather abruptly as they approach the angle) and at the dorsal entrance 

 of interbrachial or axillary channel. In the other two genera the aperture is low on 

 the side of the ray. 



APHANASTERIAS PYCNOPODIA Fisher 



Plato 70, Figures 6, 7; Plate 72, Figures 1-3 

 Aphanasterias pycnopodia Fisher, Ann. and Mag. Nat. Hist., ser. 9, vol. 12, 1923, p. 601. 



Diagnosis.- — Rays five; It 76 mm., r 7 mm., R, = 10.8 r; breadth of ray at base, 

 9 or 10 mm.; disk very -mall, rays very slender and gradually tapering to an atten- 

 uate extremity; abactinal surface well arched; marginal plates on the ventrolateral 

 margin; tube feet very crowded, sometimes five or six across the furrow; actinos- 

 tome small, sunken; adoral carina well developed; abactinal spinelets small, solitary, 

 scattered, except the carinals which form regular series; superomarginals forming 

 one. inferomarginals two. and adambulacral spinelets two regular longiseries; large 

 unguiculate straight pedicellariae; crossed pedicellariae in small circles around the 

 abactinal and superomarginal spinelets, and in tufts on the inferomarginals; gonads 

 opening dorsally. 



Pi cii/ition. — The ray has few trenchant features which may be used as recog- 

 nition characters. The well arched abactinal surface is beset with short, conical or 

 conico-cylindrical, sharp or bluntly pointed, spaced spinelets, one to a plate and 

 averaging about ().•") to 0.6 mm. in length. Those of the carinal series form a definite 

 line and are spaced about their own length apart, and are stouter than the adjacent 

 dorsolateral spinelets, which increase slightly in size toward the superomarginal 

 series. The dorsolateral spinelets are more widely spaced, do not form regular series, 

 and about four or five can be counted in the width of each dorsolateral area, at base 



