Yes, Paul's site shows the species I got and, yes, David, they are polished with subsequent loss of surface sculpture (presumably there was some).
It's obviously a venerid and what caught my attention was the surprising genus assignment.  So I bought it for $15, not the $10.80 on-line price.
Anyway, the site Paul found shows the species fairly well.
>
> From: David Campbell <[log in to unmask]>
> Date: 2007/05/14 Mon AM 11:26:56 EDT
> To: [log in to unmask]
> Subject: Re: Mercenaria menaria
>
> "Specimens have been sanded to remove the marine sediment from the
> shell and then polished. Great looking specimens. "
>
> Great looking if you like pebbles.  A little more attention to
> preserving the sculpture would make a better specimen.  These do look
> like venerids, not all that much like Mercenaria, though.  I do know
> there have been some extensive studies on Eocene faunas from the
> Indian region, which would be relatively similar geographically; the
> Paris Basin faunas might give some ideas as well, though probably few
> species in common.
>
>
> On 5/14/07, Monfils, Paul <[log in to unmask]> wrote:
> >
> >
> > Here's a site that may shed some light on what the beast may be ...
> >
> > http://www.greatsouth.net/fossils/p-F1713.html
> >
>
>
> --
> Dr. David Campbell
> 425 Scientific Collections
> University of Alabama
> "I think of my happy condition, surrounded by acres of clams"
>
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