210 PROCEEDINGS OF THE NATIONAL MUSEUM. tol. 46. 



the others irregularly roundish. Two dorsolateral series reach the 

 end of ray, the third extends about two-thirds or three-fourths the 

 length of ray, while in the interbrachial arcs are 2 additional series, 

 the plates being rather small and of secondary size. These primary 

 plates are covered with close-set, flat, or very faintly convex polygonal 

 granules, which increase very rapidly in size from the margin toward 

 the center, where 1 to several are conspicuously larger than the rest 

 and slightly more convex. The plates of second size are widely- 

 spaced, unequal, and except near the ambitus are conspicuously 

 smaller than the primary plates. They are most numerous on the 

 disk and proximal portion of ray, rather few on the outer part of 

 ray. They are convex and usually bear a relatively large hemi- 

 spherical tubercle, very much larger than the granules surrounding it. 

 Between the primary and secondary plates the integument is thickly 

 beset with very small, unequal, convex, subconical, or even spinuli- 

 form granules, largest on the center of the small intercalary ossicles, 

 and smallest on the margin of the papular pores. SmaU pedicellarise 

 with spatulate jaws, slightly higher than wide, or sometimes wider 

 than high, are scattered among the granules, which they exceed little 

 or not at all in size. Papular pores rather evenly distributed occupy 

 all this granular area, and likewise between angular dorsal extensions 

 of the superomarginal plates. There is no subdivision into areas. 

 The arrangement of the abactinal plates is similar to that in the genus 

 Asterodiscus, and unlike that of Oreaster. Ambitus bounded by 

 superomarginals, the inferomarginals being actinal. Small inter- 

 marginal plates are found at the base of ray and irregularly near the 

 tip. Furrow spines 8, the 2 central about as long as the slightly 

 curved furrow margin. Subambulacral spines 2, less often 3, becom- 

 ing 1 near the end of ray. Mouth plates with 14 to 18 furrow spines. 



Type.— C&t. No. 32632, U.S.N.M. 



Type-locality. — Tictauan Island, Mindanao. 



ASTERODISCUS HELONOTUS, new Bpecies. 



Similar in shape and general appearance to A. truncatus Coleman, 

 but differing in having smaller and more numerous abactinal tubercles 

 (of a similar form), much larger terminal superomarginal plate, less 

 conspicuous marginal plates (the superomargiaals not distinguishable) ; 

 more numerous inferomarginal plates, 9 underlying the terminal 

 superomarginal, and others bearing a large, compressed, fan-shaped 

 tubercle; flattened or spatulate actinal intermediate spines near 

 furrow, where they are larger than near margin ; only 3 furrow spines ; 

 outer subambulacral spine flattened, and heavier than the inner (the 

 reverse in truncatus); inner mouth spines shorter than the others. 

 R = 98 mm., r = 48 mm., R = 2 r ; breadth of ray at base, about 53 mm. ; 

 general form stellate, depressed. 



