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fossil, I again examined this valve. A slight view of its characters 
evinced that it belonged to the same genus : its hinge, its broad sur- 
face on the inner margin, and the broad, rougher surface to which 
the animal adhered, all agreed. 
Its muchcloser agreementwith the Panopea of Aldrovandus than with 
the Panopea of Faujas, was directly manifest. The closed valves must 
have gaped widely at both ends, and could not have made that approach 
to the cylindrical form which is observable in the latter shell. That it 
did not belong to a shell of the same species with the fossil shells of 
Mount Pulgnasco, is certain ; and that it is a valve of a small individual 
of the species P. Aldrovandi , is highly probable : there would, indeed, 
exist no doubt on this point, but that a little difference exists in the 
outline of the two shells, which however may depend on their different 
stages of growth. A representation of this fossil valve is given Plate 
XIV. Fig. 1. It has suffered a greater degree of decomposition than 
the fossils of Parma, and has lost the point of the smaller tooth. 
The fossil shell represented Plate XIII. Fig. 16, is particularly in- 
teresting from the very uncommon manner in which it is marked. It 
is little more than a cast ; being formed of a dark grey lime-stone, to 
which it appears that some of the inner plate of the shell has adhered, 
and has acquired a film of yellow pyrites. 
The valves having slipped before the forming of the cast, and hardly 
any of the shell itself remaining, it is impossible to determine under 
what genus this fossil should be placed. 
It is a transverse, regular formed, and, apparently, an equivalved 
shell, which has been marked with round, closely-set grooves, passing 
obliquely from the anterior and posterior sides ; the nearest to the 
centre meeting and forming an angle, the others terminating in the 
upper margin of the shell. 
I was favoured with this fossil by the Reverend Mr. Marsh, of Fel- 
mersham House, Bedfordshire, who found it in that neighbourhood. 
