METOPASTER MANTELLI. Al 
the length of the side about 25°5 mm. In a very finely preserved cast from the 
Upper Cretaceous beds of Haldon the length of the side is 29°5 mm. 
Locality and Stratigraphical Position—All the examples of this form with 
which I am acquainted are from the Upper Chalk. One of Forbes’s type is from 
Gravesend, but the locality of the other is not recorded. The large example 
figured on Pl. XIII, fig. 2 a, is from the Upper Chalk near Bromley. 
An extremely well-preserved cast in flint from the Upper Cretaceous beds 
of Haldon (Devonshire) is in the collection of the Albert Museum, Exeter ; and a 
cast of this example may be seen in the Museum of the Geological Survey, Jermyn 
Street. 
History.—This form appears to have been first recognised by Parkinson, who 
erroneously referred it to the Pentagonaster semilunatus of Linck. The latter is a 
well-known recent species, and quite distinct from the fossil under consideration. 
Mantell, following Parkinson’s determination, referred to the form under the 
name of Goniaster semilunata. Forbes was the first to indicate that these views 
of his predecessors were incorrect, and diagnosed the species in his memoir ‘ On 
the Asteriadz found fossil in British Strata’ under the name of Goniaster (Gonio- 
discus) Mantelli ; and figures of two examples were subsequently given in Dixon’s 
‘Geology and Fossils of the Tertiary and Cretaceous Formations of Sussex,’ 
London, 1850. Both these specimens are now preserved in the British Museum. 
Careful drawings of each fossil are given on Pl. XIII, figs. 3a and 4a. 
Remarks.—It is not without hesitation that I maintain this species of Forbes’s 
as independent from Metopaster Parkinsom. For the present, however, I 
consider it to be distinguished by the smaller size, the comparative squareness 
of the supero-marginal plates, the small size of the ultimate paired plates, as 
well as by the character of the ornamentation of the supero-marginal plates and 
of the abactinal plates. Whether a more extensive series of specimens will break 
‘down or uphold these distinctions I do not feel prepared to say. It is undoubted 
that the two forms are very nearly allied. 
I feel considerable doubt as to whether one of Forbes’s types—that shown in 
Pl. XII, fig. 4a—really belongs to the same species as the examples illustrated in 
figs. 2a and 3 a on the same plate. 
