PROCEEDINGS OF THE NATIONAL MUSEUM. 251 



similar paxilliforni groups, wliicli become smaller as tliey approach the 

 intcrradial margin; owing to this arrangement the largest and most 

 regnlar paxilhe form a star-shaped area, in which the papnlaj are 

 sitnated. The larger hexagonal paxill^e often bear 50 to 60 granules 

 and papilliie; nearly the whole of the round and slightly convex summit 

 is occupied by the central group of somewhat elevated, blunt granules, 

 which are not closely crowded; the extreme margin is bordered by 

 about the same number of smaller, longer, and more slender papilhv, 

 which spread outward, so that those of adjacent paxilhe are nearly or 

 quite in contact, except at the angles, Avhere the i)apuhTe are situated. 

 These paxilliforni groups are borne upon round, convex, columnar or 

 somewhat clavate elevations of the plates. In the triangular inter- 

 radial areas and along each side of the rays the plates are smaller and 

 closely united, without pajmlary pores, and their central elevations 

 become smaller and lower as they approach the margin, those near the 

 marginal plate becoming oblong or elliptical and closely crowded 

 together side by side in rows perpendicular to the marginal plates; 

 usually two of these rows start inward from each marginal plate along 

 the sides of the arms, but toward the center of tlie interradial area 

 three rows often correspond to a single plate. Similar plates occupy 

 the entire breadth of the dorsal area of the arms beyond the middle, 

 where no papulary pores exist, but those of the median row can be 

 distinguished even to the tip of the arm by their larger size and 

 broader form. 



The papulary pores are small, and about six surround each plate; 

 they are wanting in the triangular interradial areas and along the 

 sides and on the distal half of the rays. In e ich dorsal interradial 

 area there are two larger pores, which are usuallj^ quite easily distin- 

 guished in dry specimens even without removing the granules. They 

 are situated opposite each of the second pair of plates, counting from 

 the interradial angles, and are at a considerable distance. from the 

 marginal plates; they appear to be the genital ])ores, which are larger 

 and much wider apait than usual. 



Our largest specimen has thirty-nine upper marginal plates on each 

 radial side and a corresponding number of inferior marginal plates; the 

 former stand nearly vertically and project but little upon the disk, but 

 along the sides of the rays they advance more and more on the abactinal 

 surface. At first their height is more than three times the length, but 

 the length rapidly becomes greater and the height less, until on the distal 

 half of the ray the form is S([uarish, witli the height only a little greater 

 than the breadth. All the upper plates are covered with rather large, 

 rounded, cylindrical, capitate, unequal granules; the sutures are 

 bordered by a marginal series of small, slightly elongated, clavate 

 papilliTe, forming distinct fascioles continuous with those between the 

 lower marginal plates; the granules on the ui)per part of the plates 

 are but little elevated, but toward the lower end become larger and 



