52 FOSSIL ASTEROIDEA. 
This species was described by the late Professor Edward Forbes in Dixon’s 
‘Geology of Sussex’ in 1850 in the following words : 
** Body pentagonal, with gently lunated sides. Superior intermediate marginal 
plates four, nearly equal, plain, smooth, or minutely punctate. Inferiors similar. 
Superior oculars mitrate, large, triangular, acuminated. Ossicula of dise punc- 
tate. 
“‘ Hasily distinguished from the last species [wncatus] by its flattened mar- 
ginals and from the next [{ Hwnteri] by its lunated sides. 
**Mus. Bowerbank, from the white chalk; also in the collection of the 
Geological Survey”’ (op. cit., p. 331). 
No figure of the species has ever been published, and no record exists as to 
the specimen or specimens seen or used by Forbes as type. I have been unable to 
find any example from the Bowerbank Collection to which this name has been or can 
be applied ; and the only examples which I have seen referred to this species at all 
are four fragmentary specimens now preserved in the Museum of the Geological 
Survey in Jermyn Street, and not more than two of these could have been in that 
collection in 1850. 
After a careful study of these specimens I am bound to confess that I find no 
character by which they can be separated from Metopaster uncatus; and if the 
diagnosis is correct I am led to consider that I have certainly not seen Forbes’s 
type. The swpero-marginal plates in the specimens in question are not flattened, 
and cannot be said to differ in character from those of Metopaster uncatus. 
A possible explanation suggests itself in the supposition that Forbes inad- 
vertently mistook the actinal for the abactinal surface of the disk, a mistake which 
might easily be made by a less careful observer than the author of this species 
when dealing with a badly preserved fragment. If, however, what is really the 
actinal surface has been described as the abactinal surface the difficulty is prac- 
tically solved, for the infero-marginal plates in the fragments under notice are 
“plain, smooth, or minutely punctate.” That this is not an improbable explanation 
I would submit the following facts :—(1) that in the original diagnosis of 1848 * 
Forbes states that the infero-marginal plates are unknown; (2) that in the 
diagnosis of 1850, given above, the infero-marginal plates are stated to be 
“similar ” (to the supero-marginals) ; and (3) that notwithstanding these state- 
ments all the examples in the Geological Survey Collection are essentially actinal 
presentments of the disk, and therefore the infero-marginal plates are the plates 
1 The following is the diagnosis in full :—‘G. corpore pentagonali, lateribus lunatis ; ossiculis 
lateralibus superioribus 4, subequalibus, planis, minutissime punctatis; cnferioribus?  Ossiculis 
ocularibus superioribus magnis, triangularibus, mitratis, tumidis, acuminatis.’ (‘ Mem. Geological 
Survey of Great Britain,’ vol. 11, p. 472.) 
