METOPASTER PARKINSONI. 31 
tions for the articulation of sete. Supero-marginal plates ordinarily few in 
number, and form a broad border to the disk. Ultimate paired supero-marginal 
plates the largest of the series. Abactinal area covered with polygonal, and 
usually hexagonal, plates (some of which may have stellate bases), and upon the 
tabula are borne small, more or less co-ordinated granules. Infero-marginal 
plates more numerous than the supero-marginal series, and decreasing in size as 
they approach the extremity of the ray. Their ornamentation similar to that of 
the superior series. Actinal intermediate plates small, polygonal, covered with 
uniform granules. Armature of the adambulacral plates arranged in longitudinal 
lines. Small entrenched pedicellariz may be present occasionally on the plates. 
Metopaster differs from Pentagonaster by the large ultimate paired supero- 
marginal plates, by the comparatively small number of the supero-marginal plates, 
which are also fewer in number than the infero-marginal series, and by the 
character of the ornamentation of the marginal plates of both series. 
The forms ranked under this genus were all classed by the late Professor 
Edward Forbes under Goniodiscus, which he considered to be a sub-genus of 
Goniaster. There is, however, no justification whatever in my opinion for regard- 
ing any of the Cretaceous starfishes hitherto described as belonging to either the 
genus (foniaster or Groniodiscus. ‘The species which may be considered as the types 
of each of these genera are existing forms, and no Cretaceous forms agreeing in 
structural detail have, so far as I am aware, been discovered. Itis also erroneous 
to rank Goniodiscus as a sub-genus of Goniaster. The two genera belong to 
different families; and I am in perfect accord with Professor Edmond Perrier as 
to the limitation of the two genera. His view appears to me to be perfectly 
logical, and to be the result of careful and impartial judgment. I also consider 
that the fossil forms under consideration are quite distinct from the recent genus 
Astrogonium, as limited by me elsewhere.* 
1. MeropasteR Parkinsoni, Forbes, sp. Pl. IX, figs. 2a—2c; Pl. X, figs. 1 a— 
Se; Pl. XI, fies. ba—2e; BEE 
figs. la—ld; Pl. XVI, figs. 2a, 2b. 
PENTAGONASTER REGULARIS, Parkinson, 1811. Organic Remains, vol. iii, p. 3, pl.i, 
fig. 3 (non Linck). 
ToOsIA REGULARIS, Morris, 1843. Catalogue of British Fossils, p. 60. 
1 * Zool. Chall. Exped.,’ part li, “ Report on the Asteroidea,” 1889, p. 289. 
