> I'm an undergraduate at a WI liberal arts college (Lawrence University) with
> an interest in mollusk research, and I find myself with a question for some
> bivalve workers with local knowledge out there...
>
> I've read about certain bivalve families which have an observable proportion
> of their members demonstrating transposed hinges: ie, some part of the hinge
> of a left valve will look as though it belongs to the right valve, and visa
> versa. (Sources: treatise on invertebrate paleontology vol. 6(1), and
> Matsukuma 1996). I'm really interested in studying this phenomenon, if I
> can, but I know nothing about it outside what I've read in the
> aforementioned texts.
>
> Has anyone observed this for themselves? Where (geographically and
> taxonomically) does it seem to happen most, and in what proportions? Would
> it be reasonable to suspect that some portion of a  large-sized (n=100-900)
> random sample would demonstrate this trait, or is it super-rare?
>

I don't know of any report substantially altering the information in
those references.  I.e., carditids and unionoids are among the groups
most prone to such reversals; chamids may show reversal corresponding
to attachment (M. Campbell et al., Malacologia, 2004 has a review of
chamid systematics that may be helpful).  There are a handfull of
additional papers scattered through the literature reporting incidents
noticed of such reversal.

--
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"

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