182 
and I have some specimens of Coral Limestone from the 
last-mentioned gentleman from Steeple Ashton, which 
have sufficient of the remains of the shell to discover by 
comparison that it agrees with AZytilus lithophagus of Linn. 
Trans. vol. 8, or the other new species, which F am in- ~ 
clined to think the cross-beaked one is, although the beaks 
are only a sort of accumulated appendage. I think it ought 
to be distinguished by some title different from the usuak 
one, and might therefore be called Mytilus curvirostris. 
The signs of these, and innumerable remains of organiza- 
tion, seem to be the cause of the various spots in all 
common Flints, although they are often too much oblite- 
rated to show it, as it happens in some parts of the above 
specimens. 
The Flint appears to have first entered into the substance 
of the Coral, and then seems to have been filling up the 
spaces between the ramifications, and is in some places to be 
detected in the operation; but some Flints have the general 
shape of a Coral, but not the least resemblance in other 
particulars. I have such as show what they are by the in- 
ternal structure, from different parts of Wiltshire. 
