Thanks everyone for the shell guide info.  I can see that there isn't really
anything semi-comprehensive but still field guide sized (like a good
wildflower or birding book) and up-to-date.
I agree with the assessment on the Audubon book. I have it but I don't really
consider it a field guide.  I use it as a secondary source to check the photo
when I want to confirm something.  On the other hand it has way more shells
illustrated than the good old Golden Guide which I also have.

David Kirsh wrote:

> I'd like to second the recommendation of the Audubon Field Guide. I think
> it's best feature is that its photos are outstanding, even of micros.
>
> However, not  only do you have to jump back and forth from photos to text
> but the organization of the photos is supposedly according to their shape.
> So many related species are widely separated in the photo section.
>
> On a few days outing to the beach, I'd rather take that than any other
> single book.
>
> But how 'bout for when we get home? I've said it before: we really need
> something more up-to-date and accessible than the 25 year-old out of print
> 2nd edition American Seashells.
>
> David Kirsh
> Durham, NC