50 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Type.—Q^A. No. 30506, U.S.N.M. 



Type-locality.— ^tiition 5121, east coast of Mindoro (lat. 13° 27' 20" 

 N. ; long. 121° 17' 45" E.), 108 fathoms, dark green mud; 1 speci- 

 men. 



Distribution. — Known only from the type-locality. 



Remarks. — This species differs from G. demonstrans Perrier in 

 having, proximally, more open cribriform organs, in having a row 

 of spinelets on both series of marginal plates, larger paxillae, supero- 

 marginals in contact distally, and a different adambulacral armature. 



Genus PRIONASTER Verrill. 



Prionastcr Verrill, 1899, p. 215. 



KEY TO THE KNOWN SPECIES OF rUIONASTER. 



a *. A specialized or enlarged spine on the distal transverse border of the adam- 

 bulacral plates beyond proximal third of ray ; inferomarginal spines, well 

 developed and present on all the plates r interbrachial cribriform organs 

 more or less open. 

 b \ Siiperomarginal spine conspicuous and present on all the plates ; paxillae 

 small, 

 c ^ R=not more than 5 r ; distal superomarginals apparently in contact 

 medially ; madreporic body small with transverse striae ; cribriform 

 organs only slightly open, in interbrachium ; odd interradial double 

 series of actinal intermediate plates narrow at inner end, the series 

 not wedge-shaped ; first adambulacral perceptibly compressed ; 10 or 



11 furrow spinelets analogus, p. 50. 



c *. R=more than 6 r ; distal superomarginals not in contact medially ; 

 madreporic body large with radiating striae ; cribriform organs open ; 

 odd interradial double series of actinal intermediate plates wide at 

 inner end, the combined series wedge-shaped ; first adambulacral not 



compressed ; 12 or 13 furrow spinelets gracilis, p. 55. 



b ^ Supermarginal spine absent or very small, and present on only a part of 

 the plates ; paxillae very large ; madreporic body large with radiating 

 striae; cribriform organs moderately open; paxillar area reaching ter- 

 minal plate megaloplax, p. 56. 



a'. No enlarged spine on distal transverse border of adambulacral plates; in- 

 feromarginal spines small and sometimes absent from first few plates; 

 interbrachial fascicles closed, the combs meeting in the middle of the 

 faciole ; paxillae at base of ray with 7 or 8 central and 15 to 17 peripheral 

 spinelets ; 12 furrow spines ; actinal surface of inferomarginals minutely 

 bossed under the skin elegans. 



PRIONASTER ANALOGUS Fisher. 



Plate 3, fig. 1; plate 4, fig. 2; plate 6, fig. 2; plate 8, fig. 3, 3n-c. 

 Prionaster analogus Fishee, 1913a p. 602. 

 Diagnosis. — Superficially resembling Goniopecten asiaticus, but 

 with smaller paxillae. Differing from P. elegans Verrill in having 

 smaller and less compactly placed paxillae, an enlarged spine on 

 the distal transverse border of plate, slightly open cribriform organs 

 in interbrachium. and no minute bosses on tlie actinal surface of the 



