For many years the Marine Biological Laboratory at Woods Hole (on Cape Cod, in Massachusetts) offered an extremely useful publication called Key to Marine Invertebrates of the Woods Hole Region. As you can tell from the title, it covers more than mollusks. I just went to their website and was disappointed to see that they have removed the book from their publications list. The publication is certainly dated, but I still find it very useful. The mollusks that were in the area when it was published are still there now. And this is not an area like the Philippines where a hundred new species a year are being described. Perhaps if you contact them through their website, you can obtain a copy. http://www.mbl.edu Regards, Paul M.