42 FOSSIL ASTEROIDEA. 
3. Metopaster BowrrBankil, Forbes, sp. Pl. XV, figs. 2a—2d; Pl. XVI, figs. 
1la—l1 d. 
GontastER (Gonropiscus) BowrerBanktl, Forbes, 1848. Memoirs of the Geolo- 
gical Survey of Great Britain, 
vol. ii, p. 473. 
— — — Forbes, 1850. In Dixon’s Geology and 
Fossils of the Tertiary and 
Cretaceous Formations of 
Sussex, London, 4to, p. 333, 
pl. xxii, fig. 4. 
— = — Morris, 1854. Catalogue of British 
Fossils, 2nd ed., p. 81. 
Astrogontum BowrRBANKII, Dujardin and Hupé, 1862. Hist. Nat. 
Zooph. Kchin. (Suites 4 Buffon), 
p. 899. 
GontastER (Gontopiscus) BowrErBANnKttl, Forbes, 1878. In Dixon’s Geology of 
Sussex (new edition, Jones), 
p- 366, pl. xxv, fig. 4. 
Body of medium or rather large size. General form depressed. Abactinal 
surface flat ; actinal surface also flat, or with a slight tendency to become convex. 
Marginal contour pentagonal, with a very small amount of lunation in the sides. 
Margin thick and well rounded. 
The supero-marginal plates are five in number counting from the median 
interradial line to the extremity, or ten from the tip of one ray to the tip of the 
adjacent ray, exclusive of the odd terminal or “‘ ocular” plate in each case. They 
form a broad border to the abactinal area of the disk of uniform breadth through- 
out, which measures about 8°5 mm. at the median interradial line in the type- 
specimen described by Forbes from the collection of the late Dr. Bowerbank. 
Excepting the ultimate paired plate all the supero-marginal plates are of equal 
size. They are short and broad, the breadth being nearly twice and a half the 
length, the actual measurements in the type being length 3°5 mm. or a trifle more, 
and breadth 8°5 mm., in which case the dimensions are in the proportion of 7 : 17. 
The abactinal surface of the plates is slightly convex along the direction of the 
breadth, sufficient to define each plate distinctly. The general surface of the 
whole series is gently arched towards the margin adjacent to the infero-marginal 
plates. The height of the plates as seen in the margin is about 6 mm., and there 
is scarcely any or only the slightest diminution in height as the plates approach 
