STAKFISHES OF THE PHILIPPIXE SEAS. 271 



Inferomarginals extending laterally beyond superomarginals more 

 than in euryplax, but the plates narrower actinally, the fourth being 

 longer than wide as seen from below (eighth or ninth in euryplax) ^ 

 10 plates near middle of ray corresponding to 16 adambulacrals 

 (about 18 in euryplax). Granules slightly coarser than in euryplax^ 

 acorn-shaped, with short mucronate tips, and not conspicuously en- 

 larged on ambitus as in euryplax. 



Actinal interradial areas large; plates in 5 chevrons, rather ir- 

 regular, covered with acorn-shaped, pointed granules conspicuously 

 larger in middle of plate than on margins, and increasing in size 

 from marginal plates toward furrow ; a few are submucronate. In 

 euryplax the granules are smaller, uniform in size, and less tubercu- 

 lar. 



Adambulacrals with a slight angle on the third plate which in- 

 creases gradually on each succeeding plate, becoming fairly promi- 

 nent on the ninth or tenth, but not meeting across the furrow until 

 the middle of ray. This is due, of course, partly to the furrow being 

 more open than in some other species; the plates are not less promi- 

 nent than in euryplax. First few plates with 4 or 5 prismatic or 

 4-sided spines, these gradually increasing to 9 or 10, the median 

 being compressed, broad, and bladelike with the edge of furrow, 

 the laterals round-tipped with flat side to furrow. Proximally the 

 median spines are larger than the laterals, but far along the ray they 

 decrease in size and the distal spines are conspicuously stouter and 

 wider, though not longer. Plates are at first wider than long, then 

 for a considerable distance about as long as wide, then longer than 

 wide. Subambulacral spines and granules at first 7 or 8 increasing 

 to 15 or 18, arranged in at first 3, then 3 or 4, and finally 3 series, 

 although often a serial arrangement is hard to make out. At the 

 base of the furrow most of the subambulacrals are thick tubercular 

 spines of several lengths, and tubercular granules here and there at 

 outer end of plate. Farther along, the inner row, and the median 

 members of the second, are enlarged into stout spines, nearly or 

 quite as long as the furrow spines, while the others grade off into 

 the tubercular granules of the actinal area ; far along ray onh?^ the 

 row nearest furrow margin is enlarged, while the outermost granules 

 are slightly mucronate. No adambulacral pedicellariae. 



Mouth plates unusually small and narrow, the 2 first adambulacrals 

 nearly or quite meeting at their outer ends, behind the mouth plates. 

 Furrow spines 6 or 7, stout, prismatic. Suboral spines about 8, thick, 

 blunt, in a single irregular series. 



Madreporic body large, about twice as broad as the widest radial 

 plate; 6 plates are immediately adjacent, while 2 others encroach 

 upon it. 



Type.— C'At. No. 30544, U.S.N.M. 



