266 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Mouth plates small with short furrow margin. Marginal spines 

 6 to 8, usually 7 or 6, and similar to adambulacral furrow spines, 

 only a little heavier. Suboral spines about 10-12 in 2 series, along 

 the 2 remaining edges of the triangular plates, and granuliform 

 near the outer end of plate. The spines are graduated regularly in 

 size away from the furrow margin. 



Madreporic body small, irregularl}' hexagonal, about one-fourth r 

 from center. 



r^/pe.— Cat. No. 30542, U.S.N.M. 



Type-locaUty. — Station 5516, Mindanao Sea, oif Point Tagolo, 

 Mindanao, 175 fathoms, globigerina; 1 specimen. 



Remarks. — This species, which in form resembles N . diomedeae 

 Ludwig from the Gulf of Panama region, differs in having more 

 numerous adambulacral furrow spines, marginal plates which are 

 not tumid, inferomarginals extending laterally bej^ond superomargi- 

 nals, enlarged subambulacral granules, and a finer actinal granula- 

 tion. The abactinal plates of the papular area seem to be broader 

 and lower, and lack pedicellariae. N. euryplax closely resembles N. 

 belli (Koehler) from 250 fathoms off the Andaman Islands. It agrees 

 in having the radial and adradial abactinal plates much broader than 

 long, in having the ray broad at the base, with the fifth superomar- 

 ginal conspicuously enlarged and in contact medially, and in the 

 general absence of abactinal pedicellariae, but differs in having the 

 inferomarginals extending laterally beyong the superomarginals, so 

 that the actinal surface is wider than the abactinal. This character 

 also separates N. euryplax from N. ludtvigi Koehler and the species 

 identified by Koehler (1909, p. 54) as N. fernalis (Perrier), neither 

 of which, in addition, have the wide abactinal plates. Further. .V. 

 euryplax differs from helli in having longer, stouter, rays; the 

 2 or 3 scries of abactinal plates parallel to the adradial are not so 

 wide in proportion to length — are nearly round and have more 

 numerous granules; the madreporic body is surrounded by 6 plates, 

 not 4; the first row of suboral granules is enlarged into spines; the 

 furrow spines are 9 or 10 at the middle of ray (Koehler gives 7 or 8 

 for helli, but possibly he referred only to the proximal plates, where 

 in euryplax there are at first 5 or 6, then 7 or 8, and finally a maxi- 

 mum of 9 or 10). 



NYMPHASTER DYSCRITUS Fisher. 



Plate 62, fig. 2 ; plate 65, fig. 3 ; plate 92, figs. 5, 5a-&. 



Nymphaster dyscritus Fisher, 1913a, p. 635. 



Diagnosis. — Differing from N. euryplax in having less obviously 

 widened abactinal radial plates, slightly narrower superomarginals, 

 the sixth being as long as or longer than wide (eighth to sixteenth in 

 euryplax) when viewed directly from above; numerous abactinal 



