248 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



proximally 3 or 4 granules in a single series, or distally 5 or 6, usually 

 in 2 series. Oral spines 8, similar to the adambulacral furrow spines. 



Description. — Area of abactinal plates stellate, slightly inflated on 

 the radial areas and sunken on the interradial. Plates arranged in 2 

 regular circles surrounding the central plate, the outer circle com- 

 posed of the primary basals and raclials — 10 plates in all. Outside 

 of these the plates form a regular series along each radius to within 

 the length of 2 or 3 marginals of the tip of ray ; and from the fourth 

 superomarginal they are longer than wide, oblong, or elliptical in 

 shape, and abut against the superomarginals of each side of ray. 

 The last plate or two may be segregated by the superomarginals meet- 

 ing mediall}'. The other abactinal plates form 4 chevrons in the inter- 

 radial region inclosed by 2 adjacent radial series. All the plates are 

 rather strongly tabulate, except interradiall}^ near margin, and those 

 of the 2 circles on center of disk which are low tabulate. The radial 

 plates are wider than long and subhexagonal, the others subcircular. 

 The granules are relatively coarse, the peripheral finger-nail-shaped, 

 very slightly spaced and ornate, 10 or 12 in number on the radial 

 plates and 8 to 10 on the laterals, surrounding, respectively, 2 or 3 to 6 

 (radial) and 1 or 3 (lateral) roundish or polygonal, sometimes 

 slightly smaller, granules, spaced a little from the peripheral. The 

 large primary basal plates have upward of 16 peripheral and 6 cen- 

 tral granules. About a dozen plates, mostly adradials bear a promi- 

 nent pedicellaria, with 2 upright, oblong, or slightly tapering jaws 

 about half as long as the width of the tabulum. The plates of the 

 series separating the superomarginals are sunken slightly below the 

 surface of latter and are covered with mostly roundish, slightly 

 spaced granules. An elliptical or lozenge-shape plate usually alter- 

 nates Avith a smaller oblong one. the former being opposite the trans- 

 verse sutures of the superomarginals. Papulae in oval, radial areas, 

 reaching as far distad as the adradial plates extend, and including 

 6 longitudinal rows of plates. 



Superomarginals 13, massive and tumid, encroaching conspicuously 

 upon abactinal area, and beyond the third separated only by the 

 single series of radial plates, the last 2 or 3 being in contact medially. 

 The dorsal facet of the plate is wider than the lateral, and owing 

 to the tumidity, which is more pronounced distallj', the contour of 

 the ray is scalloped and the margin evenly rounded, having the 

 appearance of being constricted at the transverse sutures of the 

 plates, wdiich correspond on the 2 sides. The plates are covered 

 with roundish, rather coarse, subtruncate, slightly spaced granules, 

 ihose of the regular peripheral series being conspicuously larger 

 than the others on the dorsal facet but becoming subequal on the 

 lateral. The 5 or 6 plates preceding the last bear an enlarged sub- 

 central, tubercular granule 2 or 3 times the diameter of the surround- 



