602 PROCEEDINGS OF THE NATIONAL MUSEUM. tol. 43. 



lanasteridae. Paxillse large, crowded, with upward of 60 short sub- 

 equal spinelets on rather high tabula. Adambulacral plates with 

 6 to 10 jfurrow spines; the adoral conspicuously enlarged on proximal 

 plates ; also with 1 or 2 prominent subambulacral spines distally, and 

 5 to 8 proximally. 



Type.— Cat. No. 30506, U.S.N.M. 



Type-locality. — Station 5121, east coast of Mindoro, Philippine 

 Islands, 108 fathoms, dark-green mud. 



Genus PRIONASTER Verrill. 



KEY TO KNOWX SPECIES OP PRIONASTER. 



a^. A specialized Bubambulacral spine present; inferomarginal spinea well developed 



and present on all the plates. 



¥. Superomarginal spine conspicuous and present on all the plates; paxUlse small. 



t'. R equaling not more than 5 r; distal euperomarginals apparently in contact 



medially; madreporic body small with transverse striie; cribriform organs 



of interbrachium only slightly open; odd interradial double series of actinal 



intermediate plates narrow at inner end, the series not wedge shaped; first 



adambulacral plate perceptibly compressed; 10 or 11 furrow spines. 



analogiLS. 



(?. R equaling 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 spines gracilis. 



b^. Superomarginal spine absent or very small and present only on a part of the 

 plates; paxillfe very large; madreporic body large with radiating striae; 

 cribriform organs moderately open; paxillar area reaching terminal plate. 



megaloplax. 



a-. No specialized subambulacral spines; inferomarginal spines poorly developed and 

 only on part of the plates; paxillae moderately large; first adambulacral plate 

 not compressed ; 10 to 12 furrow spines elegans Verrill. 



PRIONASTER ANALOGUS, new species. 



Superficially resembling Goniopecten asiaticus, but with smaller 

 paxillae; differing from P. elegans Verrill m having smaller paxillse, a 

 complete series of marginal spines on both series, and a conspicuous 

 subambulacral spine. 11 = 105 nun., r = 23 mm., E, = 4.6 r; breadth 

 of ray at base, 24 mm. ; at eighth inferomarginal, 12 mm. Rays long, 

 slender, tapering abruptly at base, then scarcely at all until near end; 

 rays rouglily rectangular in section, the 4 angles abruptly rounded; 

 disk moderate; interbrachial arcs wide and open. Paxillse rather 

 small, close-set, the area being very narrow on outer two-thirds of 

 ray, and almost obliterated for the length of the distal 10 or 11 supero- 

 marginals, which nearly touch medially. Marginal fascioles or crib- 

 riform organs not open; furrow spines 10 or 11, and beyond base of 

 ray a subambulacral spine slightly larger than the inferomarginal 

 spine. 



