gg BULLETIN "76, UNITED STATES NATIONAL MUSEUM. 



oblique rows at sides of median radial area; pedicels high, pestle-shaped, with a 

 crown of thirty to fortv spinelets, of which about one-half form a peripheral series; 

 ubactinal i)lates feeblybbed, or round and crowded at center of disk; i)apuIiB absent 

 from center of disk and in young specimens also along median radial area; papulae 

 in fives and sbces about each plate. Marginal plates enth-ely without enlarged 

 spines or tubercles, and with deep and wide fasciolar grooves and narrow specialized 

 ridges; inferomarginals usually not extending beyond superomarginals. Adambu- 

 lacral plates about as long as broad, ^vith a furrow series of five or sLx subcylin- 

 drical bluntly pointed spinelets, and on actinal surface twelve to eighteen spine- 

 lets decreasing in size outward; those adjacent to furrow series form an irregular 

 series of five or six, the rest without defmite order as a rule. Actinal interradial 

 areas extensive; actinal intermediate plates extending two- thirds the length of ray, 

 strongly carinated and bearing a paxilliform group of rather long, slender spinelets. 

 Mailreporic body hidden; not so large as in other species of genus. Gonads extend- 

 ing far along ray in sexually mature forms. Anal aperture present, opening out 

 from an undi\'ided sac-like intestinal coecum. 



Description.— Ahact'm&l paxillar area fairly compact; paxillpe arranged in 

 obUque transverse rows at either side of median radial hne, decreasing abruptly 

 in size from inner third of minor radius toward center of disk and gradually toward 

 extremity of ray. Each paxilla consists of a shghtly lobed or roimdish base, 

 immersed in the dorsal integument, from which arises a comparatively high round- 

 tipped pedicel, broader at extremity than at base, crowTied with a divaricate group 

 of slender spinelets. A large paxilla has about fifteen to twenty spinelets in the 

 peripheral scries and an equal number forming a group in the middle. The spine- 

 lets are about half as long as the pedicel. Small specimens have fewer spinelets. 

 Abactinal plates (or base of paxillse) feebly lobed, or in yoimgest examples 

 round. In the type there are five or six very short lobes, but in small examples 

 the plates are indefinite in outline. In center of disk they are always round and 

 crowded. Papulae absent from center of disk, and along median radial area are 

 either absent or interrupted in distribution in small examples; but in type the 

 papulte extend all the way across ray; papulae in fives and sLxes about each plate. 

 Marginal plates without speciahzed spines of any sort, thus resembling Lep- 

 tychaster, and with wide, deep fasciolar channels between the raised ridges. Supero- 

 marginals, seventeen in number from interradial line, do not encroach much onto 

 abactinal surface, but are confined largely to side wall of ray. Each plate is wider 

 than long, and the raised ridges when denuded are less in thickness (or width, count- 

 ing the lesser dimension) than the intervening channels; sometimes a ridge is only 

 one-half as wide as the furrow. Each plate is covered with short, slender, and 

 blunt papilliform spinelets, becoming slenderer and longer in the fasciolar grooves. 

 Terminal plate, considerably broader than long, concave toward paxillar area, and 

 with two thimble-sliapcd spines on either side of the terminal papilla. 



Inferomarginals extending but a trifle if at all beyond the superomarginals 

 in largest specimens; in small examples, usually somewhat, toward end of ray. 

 The plates encroach conspicuously onto actinal area, to wliich they form a strongly 

 arched margin; and viewed from the side they occupy considerably more than 

 half of side wall of ray. The plates are covered with spinelets similar to those of 

 superomarginals, only thicker. 



