STARFISHES OF THE PHILIPPINE SEAS. 287 



is most prominent there are 10 or 11 furrow spines, the median slen- 

 der, pointed, compressed, witli edge to furrow, the laterals stouter, a 

 trifle longer, tapering, and with flat side to furrow. The distal facet 

 of each hypophysis is slightly hollowed out. The lateral spines of 

 4 adambulacral plates bend down over the compartment in w^hich 

 the tube feet are lodged — i or 5 from each distal facet and about 4 

 from each adoral facet, forming an effective operculum of 16 to 20 

 converging spines, Suboral granules proximally 6 to 9, conical and 

 subspinose, shorter and thicker than the furrow spines and arranged 

 in 2 series. Far along ray are about 8 or 10 conical granules in a 

 series of 5 to 7 on the outer edge of plate, with a group of 2 to 4 be- 

 tween it and the angular-furrow series. Two or three of the proxi- 

 mal plates of each series have a pedicellaria in the inner series of 

 granules consisting of 2 to 4 tapering jaws. 



Mouth plates with a fairly straight furrow series of 9 or 10 spines 

 similar to the furrow spines of the first 2 adambulacral plates, but 

 slightly more compressed, and the inner 2 or 3 are conspicuously 

 larger. Suboral granules 7 or 8 slightly spaced, the inner 1 or 2 of 

 the [median] sutural series being tuberculate. 



Madreporic body small, surrounded by 4 plates, of which the ad- 

 central basal plate is the largest; it is situated nearly halfway be- 

 tween center and margin. 



Type.— Cat No. 30550, U.S.N.M. 



Type-locality.— Station 5428, Sulu Sea, off Palawan (lat. 9° 13' N.; 

 long. 118° 51' 15" E.). 1,105 fathoms, gray mud; bottom tempera- 

 ture 49.7° F. ; 3 specimens. 



Distribution. — Known only from the type-locality. 



Remarks. — This species is remarkable for having only 4 superomar- 

 ginal and 4 inferomarginal plates in each interbrachial space; in 

 other words, the second superomarginal is the largest and is in con- 

 tact with its fellow medially. No other described species has so few ; 

 even the young specimens of arthrocnemis have at least 0. HoAvover, 

 Perricr figures some very immature forms with only 4 interbrachial 

 superomarginals, but these are tiny specimens. 



Nymphaster atopus lives in the great depths of the Sulu Sea, which 

 are pretty effectually isolated from other abyssal areas. 



Genus SPHAERIODISCliS Fisher. 



Sphaeriodiscuif Fisher, 1910, p. 171; 1911d, p. 167. Type, Stephanaster 

 bourgeti Perrier. 



SPHAERIODISCUS SCOTOCRYPTUS Fisher. 



Pliite 79, fijj. 5; plate 80, fijr. 4; plate S3, figs. 6, 7; plate 92, figs. 10, 10a. 

 Sphacriodiscus scotocryptus Fisher, 1913a, p. G41. 



Diagnosis. — In general appearance greatly resembling Ceramaster 

 granulans (except as regards the enlarged antepenultimate supero- 



