METOPASTER UNCATUS. 47 
Dimensions.—In the example figured on Pl. XII, fig. 2a, the major radius is 
27 mm. and the minor radius about 19 mm., the thickness of the margin 10 mm. 
Locality and Stratigraphical Position.—The figured example is from the Upper 
Chalk near Bromley. A number of other examples of this species are in the 
collection of the British Museum, all from the Upper Chalk, and most of them 
from the same locality, the locality of the remainder being not recorded. 
Remarks.—I was at first somewhat in doubt as to whether to rank this form 
as a variety of Metopaster Parkinson, or as a distinct species. I have taken 
the latter course. Although there are many points of resemblance in general 
structure, as well as in various details when considered independently, the facies 
of this form is so distinct from that of Metopaster Parkinsoni, and is so readily 
recognisable, that there seems to me full justification for considering Metopaster 
zonatus specifically distinct. The great breadth of the supero-marginal plates as 
compared with their length, the form and character of the ultimate plates, the 
great thickness of the margin, and the relative proportions of the marginal plates, 
as well as the general habit of the abactinal surface, apart either from the 
individual characteristics of the plates independently or from other special details, 
are amply sufficient to distinguish the form from its nearest ally, Metopaster 
Parkinsoni. 
5. Meropasrer unoatus, Forbes, sp. Pl. XI, figs. 3a, 36; Pl. XIV, figs. la—s3; 
PIOXV, figs: Was to: 
GontastER (Gonropiscus) uNcATUS, Forbes, 1848. Memoirs of the Geological 
Survey of Great Britain, vol. i, 
p- 472. 
— — — Forbes, 1850. In Dixon’s Geology and 
Fossils of the Tertiary and Creta- 
ceous Formations of Sussex, London, 
Ato, p. 331, pl. xxi, figs. 4, 5, 8. 
— — _— Morris, 1854. Catalogue of British Fossils, 
2nd ed., p. 81. 
ASTROGONIUM UNCATUM, Dujardin and Hupé, 1862. Hist. Nat. Zooph. 
Fchin. (Suites 4 Buffon), p. 399. 
Gontaster (Gonropiscus) uncaTUs, Forbes, 1878. In Dixon’s Geology of Sussex 
(new edition, Jones), p. 365, pl. xxiv, 
figs. 4, 5, 8. 
