Hi Linda, I'll see what I can figure out; I'm an amateur's amateur. But I can recommend trying the book Sea Shells of Tropical West America by Myra Keen (Stanford University Press, c. 1971). I've been using it to id shells I found in Puerto Vallarta in March; it's helpful because it has stuff not in the Compendium everybody talks about. If your local library doesn't have it, maybe they can borrow a copy through their Interlibrary Loan Dept. Hope this helps! Sue in Denver