>I would like to offer a point, each, regarding shells damaged by drilling
>and shells damaged by wear, probably not from wave action.  First, my
>collection includes only one shell to which I have given a personal name,
>and it remains one of my favorites.  I call it "Dumb and Dumber."  It is a
>live-taken Pteropurpura with two holes drilled, one into the ventral
>aspect, midway along, axially, the callus.  Somehow, it appears to have
>missed the critter.  That was "dumb," but dumber was the hole drilled
>completely through the wide, flared lip, with no reasonable expectation of
>hitting the retracted animal.  Secondly, I have taken two Volutopsius
>furukawai (I think) which I got alive although their shells, just
>posterior to the aperture, on the ventral aspect, were worn all the way
>through, with the animal bulging partly out the irregular wear opening.
>The shells are otherwise quite intact and strong, except where worn
>through as stated.  Most Volutopsius, including a lot of
>middendorffi/emphaticus I get are worn "bald" there, through their perio,
>and several hsve been worn quite thin there, some even with slight holes
>worn through, but these two are the only ones I found substantially
>exposed to attack, in that way.

Come to think of it, I have a specimen worn through there as well.

>I am curious to learn on what terrain
>they are dragging their shells so abrasively.

The position of the wear is not correct to be caused by substrate. It
can only be the operculum causing this.
--
Andrew Grebneff
Dunedin
New Zealand
Fossil preparator
Seashell, Macintosh, VW/Toyota van nut
‚ Opinions stated are mine, not those of Otago University
"There is water at the bottom of the ocean"  - Talking Heads

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