James,
 
I think there may be one on Poppe's site but I know there is a nice one
on Eddie Hardy's web page.  Just select gastropods, then the letter of
the species in question (in this case "s"), then select Gaza superba and
viola!! a nice image.
 
All at http://www.gastropods.com/shell_pages/index.html
 
Tom Eichhorst in New Mexico, USA