SHALLOW-WATER STARFISHES 237 



ossicles everywhere covered with even, fine, slender, upright, 

 crowded spinules, which largely stand in two or three close rows on 

 the larger ossicles, and sometimes in single, comb-like rows, around 

 and between the papulae. The larger groups are often curved or 

 crescent-shaped. These spinules are longer and more slender than 

 in ordinary H, sanguinolenta, and have rough, acute, or subacute 

 tips. They diverge but little. The papular pores are rather large 

 and mostly isolated. The madreporic plate is of fair size, rough, with 

 rows of small spinules on the gyri. 



The dorsal ossicles, when the spines are removed, are small, 

 thick, convex, often narrow-oblong. They form an open reticulation 

 in which the smaller meshes are polygonal or irregularly triangular. 

 The upper and lower marginal plates are easily distinguished by 

 their larger size and more convex surface. The two rows are con- 

 tingent on the distal third of the rays, with large papular pores 

 between them. They become separated by a row of small rounded 

 ossicles, increasing in size proximally. Two or three other rows of 

 small, irregular intermarginal ossicles are also interpolated at the 

 base of the rays, in the lateral interradial areas, where the upper and 

 lower marginals are widely separated. The superomarginals are 

 prominent, with a narrow transversely oblong surface. The infero- 

 marginals are larger, with the exposed surface sometimes angular, 

 or transversely oblong, sometimes curved or crescent-shaped, with a 

 narrow, prominent ridge for the insertion of the spines. They are 

 always decidedly longer transversely to the rays ; the transverse 

 diameter is often double the longitudinal. When curved, the con- 

 vexity is toward the base of the ray. Some of the proximal ones 

 are much compressed, with a rather sharp ridge, and bear only one 

 row or comb of spinules. 



The peractinal ossicles form but one row, though often the row 

 is irregular. They are somewhat rounded or lobate lozenge-shaped, 

 and much smaller transversely than the inferomarginals, but equal 

 to them in number. The two rows are united by apophyses, between 

 which is a row of large papular pores. They are united directly to 

 the adambulacral ossicles, with which they agree in length. The 

 latter are transversely oblong and prominent. 



The spinules on the superomarginal and lateral ossicles are about 

 the same as those of the dorsal surface, but on the inferomarginal 

 plates they become a little larger and longer. On the inferomarginals 

 they mostly stand in two rows, of about eight to sixteen each, along 

 the middle of the rays ; but beneath the disk they may be reduced to 



