>  >Bivalves with hinge teeth typically have different teeth in the left
>  >and the right, and there are rare individuals with the teeth swapped
>  >around, analagous to sinistrality in snails, except that some groups
>  >of teeth may swap while the others are normal.
>
>  I have heard of this, but never seen one, nor good images. Is the
>  entire hinge transposed, or is it that the hinges are deformed so as
>  to somewhat resemble transposed teeth?

Either the entire hinge is transposed, or discrete sets of teeth are transposed.  The Treatise on Invertebrate Paleontology has figures and some of the major references.

>>(or maybe not even true snails!).
>  Referring to Macluritoidea and Euomphaloidea? I think the presence of
>  an operculum is  evidence, if not proof, that these are gastropods.

Pelagiellids, which do not have a known operculum, are one group that might not be true gastropods despite the coiled shell; some bellerophotiform shells likewise might not be snails.  I think Paul Morris had a paper in the AMS bulletin recently that did some functional morphological analyses on whether torted or untorted animals would work better in some of the problematic Paleozoic forms.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL  35487-0345 USA
    [log in to unmask]

That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa

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