This was one of the great things about Conch-L!

Thanks to Andrew Dickson's directions, and subsequent  checking of images on Rich Goldberg's site, I am sure my
shell is "Scaphella junonia butleri"  Clench, 1953, from the Gulf of Campeche Mexico.   (This is the locality given in the Compendium.   As is often the trouble with buying old collections, there was no data available for this shell.

Cheers,
Linda