>Fellow Conch-Lers,
>
>Nicholas Zantopp, a young (yes, 11 years old) shell collector from Fort
>Lauderdale, FL, is visiting the collection area of the Shell Museum. He and
>his mom came to participate in the (once again) excellent Sanibel Shell
>Show. I am trying to find, following his request, if any of you out there
>know of any published information on the phenomenon of double opercula.  He
>has found a medium-size apple murex (Phyllonotus pomum) that had two
>opercula (the animal and shell otherwise look normal); far I couldn't find
>any paper(s) or other information that could help Nicholas in his quest for
>the double-opercular truth. Best to all,
>
 
This might be associated. I don't have the paper before me (it's at the
office) but it comes up with the keyword "operculum" in my database:
 
Honigmann, H. L. 1912. Uber Doppeldeckelbildungen bei Nassa mutabilis
(Linne). Zoologischer Anzeiger 39(23-24):689-692; 3 figs.