STAEPISHES OF THE PHILIPPINE SEAS. 457 



spiny tips, whence " corynetesP On the largest paxiUae, at base of 

 ray, the peripheral spinelets are a trifle short of 2 mm. long, while 

 the central, clavate, truncate in form, is about 1.5 mm. long. There 

 are no deposits in the supradorsal membrane. Osculum small, closed, 

 the special spines forming a low protuberance. 



Adambulacral combs with 7 spines, the inner end of each series, 

 comprising the first 3 spines, bent obliquely downward and aborad. 

 The inner spinelet is very short, one-half to two-thirds as long as 

 the second ; the second, two-thirds the length of the third ; the next 

 4 increasing slightly in length, the outermost being generally the 

 longest, although the difference in the length of the outer 3 is not 

 great. Membrane between the spines, which are sharp, slightly 

 emarginate. Aperture and papilla small, the papilla broad, and 

 round-tipped. Distal combs with 6 spines. 



Mouth plates with 5 marginal spines, increasing rapidly in length 

 from the outer, which is short, toward the innermost, which is half 

 again as long as the median suture. All 10 spines of each mouth pair 

 united by a continuous membrane. Three pairs of plates are entirely 

 without suboral spines; one pair has a spine on 1 plate, while the 

 fifth mouth angle has a suboral spine on each plate. This spine is 

 nearly as long as the imier marginal spine, and is slender, tapering, 

 with a sharp hyaline tip. 



Actinolateral membrane broad, the margin defining ambitus, but 

 not forming a conspicuous fringe. The tips of most of the actino- 

 lateral spines can be seen from above. Actinolateral spines stout, the 

 tip slightly flaring as a rule and truncate; sixth spine reaching mar- 

 gin of membrane. The first 5 spines meet or cross the tips of their 

 fellows of adjacent ray along the interradial line. Owing to propor- 

 tions of r to R, the actinal interradial areas are not very board, al- 

 though the entire actinal floor outside the adambulacral fans is oc- 

 cupied by the actinolateral membrane. At the sixth actinolateral 

 spine, half the distance from furrow margin to ambitus is occupied 

 by the adambulacral fans ; at middle of ray, measured along side, a 

 little more than half. 



Type.—C2ii. No. 37014, U.S.N.M. 



Type-locality. — Station 5623, Molucca Passage, 7.5 miles northeast 

 Makyan Island (lat. 0° 16' 30'' N.; long. 127° 30' E.), 272 fathoms^ 

 fine sand, mud; 1 specimen. 



Distribution. — Known only from the type-locality. 



Remarks. — In my key to the species of Pteraster (1911<Z, p. 368) 

 Pt. corynetes belongs to the second section, although the rays are 

 slightly longer than in the other species. Among those species having 

 all the oral spines united by a continuous membrane, only 5 are 

 comparable with corynetes., namely pulvillus^ tem/nochiton, rugdtus, 



