NYMPHASTER. 75 
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 pedicellariz, and there are no spines, 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. (1885) p. 602 ; ed. Chall. Rep. 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, Perr. Nouv. Arch. Mus. vi. (1884) 
p. 234, pl. vi. figs. 1 & 2. 
Nymphaster protentus, Sladen, Chall. Exp. Ast. (1889) p. 303; 
Bell, Ann. § Mag. iv. (1889) p. 485; Sladen, Proc. R. Irish Acad. 
i. (1891) p. 694, 
Nymphaster subspinosus, Norm. in Bourne, Journ. Mar. Biol. Assoc. 
ij. (1890) p. 827. 
R= 4r (nearly). 
Arms five, taper rapidly ; superomarginals touch along middle 
