XT3IPHASTER. iO 



innermost are longer than wide ; one or two about the middle of 

 the row tend to be square, and the more external are wider than 

 long ; the terminal superomarginal plate is elongated, and the more 

 so when there are seven than when there are eight plates, while 

 the terminal inferomarginal plate is triangular. The abactinal 

 plates of the disk are uniformly granulated and are irregular in 

 shape, with a not very well marked tendency to be hexagonal in 

 form. The ultimate, and sometimes also the penultimate, supero- 

 marginal of either side of each arm is not separated from its fellow 

 by any of the abactinal plates. 



The granules of the plates of the actinal are somewhat coarser 

 than those of the abactinal surface ; on each side of the middle line 

 of the arm there are two rows of plates, one of which extends to 

 the end of the arm and the other halfway. The adambulacral 

 spines are short and square at their tip, so that they differ hardly 

 at all from the granules of the adjacent plates ; they are arranged 

 in a single row, and there appear to be five on each adambulacral 

 plate. The groove is exceedingly narrow, and the tube-feet are not 

 to be seen in the single specimen collected. There are no signs of 

 any pedicellariae, and there are no spiues. The madreporite is 

 undistinguishable. The appearance of the specimen in alcohol is 

 somewhat leathery, owing to the comparatively thick membrane 

 with which it is invested. 



a. South-west coast of Ireland, 1000 fms. (Type.) ' Flying Fox ' Exp. 



Only one specimen is known at present. 



2. NYMPHASTER. 



Nymphaster, Sladen, Chall. Narr. i. (188-5) p. 602; id. Chall. Pep. Ast. 

 (1889) p. 294. 



Flattened, with elongated arms formed by the marginals alone or 

 by them and a single row of intermediate plates. Intermediate 

 plates of dorsal surface with flat tops, ordinarily hexagonal in form, 

 not extending beyond the disk. Adambulacral spines in longitu- 

 dinal rows. Spines on inferomarginals reduced or absent. 



1. Nymphaster subspinosus. 



Pentagonaster subspinosus, Pen: Nouv. Arch. Mus. vi. (1884) 



p. 234, pi. vi. figs. 1 & 2. 

 Nymphaster protentus, Sladen, Chall. Exp. Ast. (1889) p. 30-3 ; 



Bell, Ann. § May. iv. (1889) p. 435 ; Sladen, Proc. R. Irish Acad. 



i. (1891) p. 694. 

 Nvmphaster subspinosus, Norm, in Bourne, Journ. Mar. Biol. Assoc. 



i. (1890) p. 327. 



R = 4 r (nearly). 

 Arms five, taper rapidly ; superomarginals touch along middle 



