196 



it belonged to the same genus : its hinge, its broad surface on the inner 

 margin, and the broad, rougher surface to which the animal adhered, all 

 agreed. 



Its much closer agreement with 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. J/flfrwwzd/, is highly probable : there would, indeed, 

 exist no doubt on this point, but that a little difference exists in the out- 

 line 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 fos- 

 sils, of. Parma, and has lost the point of the smaller tooth. 



The fossil shell represented Plate XIII. Fig. 16, is particularly inte- 

 resting 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 wjiat 

 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- 

 tnersham House, Bedfordshire, who found it in that neighbourhood. 



