i<2 j\Ir. A. Alcock on 



the abactinal surface of the disk and rays, directly super- 

 jiosed to the iiifero-maiginali', phvte to phite. 



Abactinal surtacc covered with close-set paxillaj, which on 

 the rays are arranged in curved transverse rows without any 

 cidarged median series ; papuUe distributed everywhere 

 between the paxillaj. 



Actinal intermediate areas large, extending far along the 

 ray; the plates closely covered with coarse spinelets. 



Adambulacral phites with a furrow-series of obtuse, com- 

 pressed, slightly radiating spinekts, and aetinally with two 

 longitudinal series of coarse pa])illiform spinelets. 



All the spinelets on the actinal surface of the animal are 

 covered with membrane and are grooved, somewhat resembling 

 pedicellaria3 to the casual view. 



Anus distinct, subcentral. Madreporiform body small, 

 concealed, distant from the margin of the disk. 



Ko true pedicellariai are present. 



The generative glands have the usual position in the inter- 

 brachial arcs. 



The ambulacral furrow is remarkably wide. 



This genus was first defined in the Ann. & Mag. Nat. 

 Hist., Dec. 1891, p. 430. The examination of further 

 material now permits more precision in the definition. 



10. Persephonaster croceus, Alcock and Wood-Mason. 

 (PI. IV. figs. 1, 2.) 



Perseplionaster croceus, Aim. & Slag. Nat. Hist., Dec. 1891, p. 430. 



Kays 5. l{ = 4-5 r. 11 = 95 millim. in the 

 type specimen. 



Disk and rays quite rigid, their abactinal surface covered 

 with close-set spinose paxillre, which become small and very 

 crowded towards the subcentral anal aperture, and are arranged 

 in transverse series on the rays ; a few incipient pedicellariEe 

 adjoin the marginal plates on the disk ; the whole abactinal 

 surface is perforated by close-set ])apu!a>. 



The very massive sujjero-marginal plates number 31, and 

 are directly superposed on the infero-marginals, plate to 

 plate ; each is coarsely granular in the centre and finely 

 spiuulate at the edges, and each bears two sharp rigid spines, 

 one at the abactinal, tlie other near the actinal end, the former 

 being the smaller and often bifid. 



The massive infero-marginal plates correspond, plate to 

 plate, with the supero-marginals; they are uniformly covered 

 with paijillifcrm granules, which are largest in the middle of 

 the ])late, and each bears near its upper (abactinad) end a 



