76 ^fr- A. Alcock on 



2. rararcliaster Iluddlcatonii, sp. ii. 



Rays 5. R = ll r. E, = about 170 millim. in the 

 type specimen. 



Disk very small ; rays depressed, very long, tapering. 



Abactinal surface covered with small, rather distant, 

 unequal-sized nodular plates, each of which bears a single 

 erect acute spine or spinelet, the spines on the disk being 

 very stout and measuring in the type specimen 5 to S 

 millim. in length, while the spinelets on the rays are small 

 and slender and decrease in length from about 2 millim. near 

 the base to less than a millim. at the periphery of the ray. 



Supero-marginal plates more than 60, entirely lateral and 

 slightly oblique in position, elongate, oval, tumid ; each with 

 a central tubercle bearing a stout acute S])ine with a basal 

 circlet of spinelets, one of which is sometimes considerably 

 enlarged, especially in the interbrachial region ; the odd 

 interbrachial plate is in the form of a salient eminence, upon 

 which stands a spike of preeminent size with a basal circlet 

 of spinelets larger than those on the other plates. 



Infero-marginal plates alternate with the supero-marginals 

 and very oblique, elongate, pyriform, tumid ; each bears 

 usually three stout sharp spines in an oblique series, the most 

 abactinal being the largest and often having at its base a pair 

 of spinelets ; in the interbrachial arc the spines, especially 

 those of the odd plate, are a good deal aborted. Tlie intervals 

 between the infero-marginal plates throughout the ray are 

 occupied each by a large multivalve or pectinate pedicellaria. 



Adambulacral plates large, broad, tumid, each with a 

 furrow-series of six to eight compressed obtuse spinelets in a 

 semicircular comb, and with three spinelets obliquely placed 

 on its actinal surface, the two of these nearest the furrow 

 being of conspicuous size. 



Mouth-plates large, each with a furrow-series of six or 

 seven spinelets, increasing in size from periphery to centre, 

 and with a suture-series of three much larger spinelets. 



Actinal interradial areas very small, not extending beyond 

 the second or third marginal plate; the intervals between the 

 plates occupied by large multivalve (pectinate) pedicellarige, 

 but the ])lates are otherwise quite unarmed usually. 



Anus subcentral. Madreporiform plate large, subcircular, 

 flat, with fine radial striations. 



Ambulacral furrow wide ; tube-feet very large, with a 

 small sucker at point. 



Papulae confined to rudely stelliform areas at the very base 



