96 Mr. A. Alcock on 



30. Nymphaster nora^ sp. n. 



Rays 5. E=6-3 r. R = 120 millim. in the 

 type specimen. 



Disk small, flat, pentagonal ; ra^'s very long- and slender 

 and tapering, quadrangular in section, but at the tip cylin- 

 drical ; interbrachial arcs wide. 



Abactinal area of the rays entirely occupied by the supero- 

 marginal plates, which from the fifth onwards meet across 

 the lay ; abactinal area of the disk covered with hexagonal 

 paxilliform plates, which consist of a slightly raised tabulum 

 closely covered with angular many-fncetted granules, of which 

 six to nine form a central group and twelve to sixteen a 

 marginal ring ; of these plates the basal interradials are the 

 largest, but those in the radial areas, especially those in the 

 mid-radial line, are also very large ; papulae are found in the 

 radial areas only, emerging at the angles of the plates. 



The marginal plates number about 40 in each series, they 

 are quadrangular and massive, and are closely covered with 

 angular granules Avithout any other armature ; each supero- 

 marginal articulates with two infero-marginals unequally. 



The supero-marginals of opposite sides, from the fifth 

 onward, meet across the ray, plate to plate, in a straight 

 suture* each plate presents a broad abactinal plane and a 

 narrow lateral plane, and at the junction of these two planes 

 an inflated angle; the cap-like terminal plate bears five spines 

 in a half hoop. 



The infero-marginals are smaller than the supero-marginals; 

 their lateral surface, except in the interbrachiura, is twice the 

 breadth of the actinal surface, and the angle at which the 

 two surfaces meet is so inflated that the rays, whether viewed 

 actinally or abactinally, seem to have beaded or festooned 

 borders. 



The large adambulacral plates completely close the furrow, 

 the distantly isolated pairs of tube-feet emerging from semi- 

 circular gaps which, by the close apposition of the plates of 

 opposite sides, become isolated circular holes. Each adambu- 

 lacral plate is, in fact, rudely L-shaped, the broad horizontal 

 limbs of the L's meeting across the furrow, and the much 

 restricted concavities of the L's forming the gaps which, by 

 the apposition of the plates, are converted into closed 

 chambers;, actinally the plates are closely covered with 

 granules, while on the furrow-edge each plate has about 

 twelve long compressed spinelets arranged (except in the case 

 of a few plates close to the actinostome) in two divergent 



