If anyone would like to see the sexual dimorphism of Viana regina,
there is a picture on Bret Raines' "what is it?" page.  Go to
http://www.molluscs.net/whatisitf.htm
The bottom picture on the page (Photo 20) shows 24 Viana regina,
including several of the notched-lip males and several of the
smooth-lipped females.  Click on the picture for a closer view.
Paul M.