166 
stone, but they display enough of the hinge to prove that 
it has one elongated irregular tooth: one of them (fig. 
3.) shews the concentric lines of a single muscular im- 
pression very neatly ; but I am unable to trace indications 
of two upon either of them to make their generic cha- 
racter complete. Three of the specimens have conside- 
rable portions of stone attached to them; as they would 
render the shells less conspicuous I have omitted them 
in the figures, which, even now, are not so perfect as 
might have been desired ; but experience teaches us that 
we must depend much upon such specimens for our know- 
ledge in geology, and rest satisfied when they are perfect 
enough for us to trace the identity of species. 
Long Comb Girts, in the parish of Sudbury, near 
Sidmouth, where these specimens were found, is the only 
spot, I am informed of, that produces this species. 
The attached valves have not been met with; they 
have probably been left adhering to the rocks from which 
the others were washed, previously to their being depo- 
sitedin the situation we now find them preserved in. 
