228 BULLETIN 76. UNITED STATES NATIONAL MUSEUM. 



a single series of granules, ami bearing besides occasionally a central granule, 

 rarely a tubercle, and (interradially) here and there a large low bivalved pedicel- 

 laria. Marginal plates regular, large, dorsally and ventrally naked except for a 

 peripheral series of granules; a cluster of granules with sometimes a spine or tubercle 

 on outer face; no marginal i)edicellariiB; scattered large bivalved actinal pedicel- 

 lariie; actinal granules large; adambulacral spines two, large and clavate in a trans- 

 verse row on plate, the furrow spine slightly the larger. 



Description. — Abactinal plates large and small intermingled, the larger or pri- 

 mary plates not arranged in very regular order, the median radial coming nearest 

 to forming a series; and that only on outer part of major radius. Periphery of 

 plates surrounded by a single series of rather large ovate, acorn-shaped, or com- 

 pressed granules blunt or pointed and of unequal size. The surface of the plate is 

 smooth and flat, but occasionally the center of a primary plate has one or two 

 thimble-sha]icd granules, those on the radial series very rarely enlarged into short 

 tubercular spines. A specimen more often has no abactinal tubercles, or only one, 

 two, or three. The specimen photographetl has more than any other. Scattered 

 over the dorsum chiefly on the interradial areas is a variable number (fifteen 

 to sixty-five) of low bivalved pedicellarias occupying whole width of plate, the 

 jaws lower than the combined breadth of the two jaws. The flat or very gently 

 convex bare surface of the abactinal plates (except those bearing pedicellaria; or 

 an occasional central granule) is one of the most characteristic features of tins 

 species. 



Marginal plates conspicuous, encroaching conspicuously upon both surfaces. 

 Superomarginals six to nine; inferomarginals one more. Most of the superomargi- 

 nals wider than long, the abactinal surface slightly tumid and bare, with a periph- 

 eral scries of granules similar to those of neighboring abactinal plates but usually 

 more compressed and wider than high. Actinal surface of inferomarginals similar 

 but the naked surface a little larger and less convex and the granules even more 

 regular. Outer face of both series covered with unecpial ovoid, subglobose, round- 

 ti])])ed or pointed tubercular granules larger than those of dorsum. The granular 

 surface of superomarginals larger (that is, higher) than is that of inferomarginals; 

 one to four granules are enlarged, and frequently one or less often two are 

 developed into short blunt tubercular spines, the superomarginal spines being the 

 longer. There is great irregularity in the occurrence of these spines which are more 

 numerous, irrespective of age, on some specimens than on others. Near the end 

 of ray there are fewer granules, and the jilates frequently bear only the peri])heral 

 series and a tubercle with several granules near the aboral edge, or only one to 

 several granules. Terminal ])late subglobose fairly large with or without granules 

 and one tubercle. 



Actinal interradial ])lates irregular with large unequal peripheral granules, 

 tkose on the edge toward marginal plates being largest as a rule. In each inter- 

 radial area adjacent to adambulacrals are from two to nine long low bivalved pedicel- 

 laria?, with an imdulating smooth or sparsely serrate edge to jaws. These are longer 

 but not higher than the dorsal i)edicellariae, the largest as a rule being near the 

 base of furrow. 



