It's interesting to hear that Cypraecassis loses its operculum before
adulthood. I would have thought that it would be retained, as in other
cassids.

The use of opercs as diagnostic characters is more tricky than one
might think. Some species have very variable opercs; for instance,
that of Sassia kampyla may be typically ranellid, with the nucleus at
the anterior end, or it may be concentric with a central nucleus.
Volutomitra banksi usually seems to have no operc when adult, but I
have collected one specimen with a minute operc. I have also collected
a small Conus in Victoria, Australia which had no operc.

As all gastropods have an operc at some stage, I suppose that in an
abnormal specimen of a normally-inoperculate species, say a
marginellid or a "bubble" snail, the operc might be retained into
adulthood...

--
Andrew Grebneff
Dunedin, New Zealand
Fossil preparator
Mollusc, Toyota & VW van nut

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