42 FOSSIL ASTEROIDEA. 



3, Metopastee Boweebankii, Forbes, sp. PI. XV, figs. 2 a — 2d; PI. XVI, figs. 



1 a— 1 d. 



GoNiASTEE (GoNiODiscTJs) BowEEBANKii, Forhes, 1848. Memoirs of the Geolo- 

 gical Survey of Great Britain, 

 vol. ii, p. 473. 



— — — Forhes, \S50. In Dixon's Geology and 



Possils of the Tertiary and 

 Cretaceous Formations of 

 Sussex, London, 4to, p. 333, 

 pi. xxii, fig. 4. 



— — — Morris, 1854. Catalogue of British 



Fossils, 2nd ed., p. 81. 



AsTBOQONiUM BowEEBANKii, Dujardin and Supd, 1862. Hist. Nat. 



Zooph. Echin. (Suites a Buffon), 

 p. 399. 



GoNiASTEE (GoNioDiscus) BowEEBABTKii, Forhes, 1878. In Dixon's Geology of 



Sussex (new edition, Joues), 

 p. 366, pi. 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 Foi'bes from the collection of the late Dr. Bowei'bank. 

 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 sei'ies 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 



