Laws aside since I will research this as needed, I am looking for a guidebook on shellfish. Ideally, it would also indicate the general locations in which they can be found.
I'm looking for a book or website where I can see a picture of a shell and have an idea of whether it is sweet, or briny or which are better suited for chowders vs different preps. I understand that water in the area plays a strong part, but in New England, I can go to the sea and identify the different tasty species and know right away which are chowder clams and which can be enjoyed eaten on the half shell.
Last year I rented a house in southern Italy where snails and clams were plentiful. I plan to return this year so I'd like to be armed with knowledge.