Hi Debbie,

Two books come to mind.  "Moluscos Marinos Del Norte De Chile" by Jorge
Basly, which is in Spanish, but it does have photos and the "Latin names are
in English". The other book is "Intertidal Mollusks of Iquique, Chile" by
Louie Marincovich (published by the Natural History Museum of Los Angeles
County).  You might also try "Seashells of Tropical West America" by Keen.  I
have all three books, but I don't know of a source for them off hand.  Hope
this helps.

Happy Shelling,

Richard Sedlak