108 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



rower. Paxillae large, crowded, nearly flat topped, arranged on the 

 rays in slightly curved, transverse series, the regularity of which is 

 interrupted proximally and distally along median radial lines. At 

 base of ray 3 rows correspond to 1 superomarginal. The largest 

 paxillae are on the disk about two-thirds distance from center to 

 inner edge of marginals, and on the proximal fourth of ray on a 

 broad radial area. The paxillae decrease in size very gradually 

 toward center of disk, periphery of area, and end of ray. They have 

 the appearance of being fairly uniform in size. The larger paxillae 

 have 15 to 20 peripheral and 10 to 12 central, very short, almost 

 granuliform, round tipped, minutely prickly spinelets. Owing to 

 their crowded disposition the crowns of the paxillae vary from sub- 

 circular to polygonal. 



The dorsal plates or bases of paxillae, are elliptical with 4 to 6 

 incipient lobes, so that the plates may appear somewhat 6-sided, 

 though longer than wide. On the median radial area, where there 

 are no papulae, the plates vary from elliptical and lozenge shape to 

 broadly oval, and are close-set or proximally even slightly overlap- 

 ping. On the papular areas of outer part of ray the plates are quite 

 independent, but on disk and proximal portion of ray the}- touch 

 by the incipient lobes. The plates are true paxillae, as the shaft is 

 constricted in the middle — that is, flares at top and bottom. Papulae 

 small, six about a plate, but absent from a median radial band, where 

 the plates are elongate and crowded. 



Marginal plates very massive. Superomarginals unarmed, en- 

 croaching conspicuously upon paxillar area, 34 in number, and form- 

 ing a well-rounded border to abactinal surface. The plates are wider 

 than long and there is a distinct abactinal and lateral face to each. 

 The plates are separated by abrupt, rather deep, fascioles, narrowei- 

 than the intervening ridges, and more like those of Psilaster than 

 the more or less abortive V-shaped grooves of P ersefhonoMer and 

 Blakiaster. The exposed surface of this ridge is slightly tumid, espe- 

 cially on the outer part of ray and the summit of the ridge is near 

 the distal margin, as in such species of PersepJumaster as curyactis 

 and liizonlcus. 



Exposed surface of plate covered with rounded, nearly flat 

 granules, which gradually are transformed into slender spinelets of 

 the fasciolar grooves. Terminal plate subovoid with 3 stubby spine- 

 lets on the end. 



Inferomarginal plates opposite superomarginals, except some- 

 times on outer part of the ray, and with a rather broad rounded 

 actinal surface passing imperceptibly into the lateral. They do not 

 extend laterally beyond superomarginals. Rather deep fascioles sep- 

 arate the plates, which, on the tumid outer end, are armed with a 

 vertical oblique comb of proximally 6. distally 4, appressed, slightly 



