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gently disposed, as to have every good and illustrative specimen, in such 

 a situation as shall best allow of its examination. 



We have thus seen the same roundish oyster at Plumstead, Wool- 

 wich, and Bromley ; but I was not able to find, either at Plumstead or 

 at Bromley, the long oyster, the remains of which were discoverable at 

 Woolwich. On Bexley Heath, however, about three miles from Wool- 

 wich, in a south-east direction, a species of oyster is found, at two or 

 three feet beneath the surface, in the mould, which seems to be similar 

 with that of Woolwich; and is, at the same time, in a much better state 

 of preservation. 



The Bexley oyster is from two to three inches in length, and from one 

 to one and a half in breadth. The outer surface is rough. The impres- 

 sion, is rather large ; and the cartilaginal pit, which is finely striated in 

 a transverse direction, is formed on a vaulted surface of half or three 

 quarters of an inch in length, beneath which vaulted surface a part of 

 the animal must have been disposed. 



The shell, which seems, more than all others, to deserve to be termed 

 O. fornicata, is one which, from the appearance of the adherent matrix, 

 I suspect to have been found on the Hampshire coast. It is about two 

 inches in length, and one and a half in breadth. Its outer surface is pretty 

 smooth. On its inner surface, the margin is seen, finely striated, con- 

 centrically, by the added lamellae of growth. The mark of adhesion is 

 about the middle of the shell, and there is no appearance of any pit. But 

 the circumstance most interesting, in this shell, is a vaulted floor, sunk 

 rather more than the eighth of an inch below the margin, and extend- 

 ing from the beak to the middle of the shell. A part of the animal must, 

 of course, have existed beneath this floor, as the mark of adhesion is 

 formed just beneath its edge. 



I have a single valve of an oyster-shell, from Carshalton, which is about 

 four or five miles south-west of Bromley : but this valve is larger, longer, 

 and flatter, than those belonging to the shells already described. The 



