Hi Tom & Paul
American Seashells only has 2 Editions.

However, Compendium of Seashells has 3, and is in its 7th printing.
Other than cosmetics is identical to the
"American Malacologist Inc" - 3rd Printing

1st Printing / 1st Ed =  EP Dutton 1982
§  2 errata sheets were available as inserts, dated Dec 1982 & Feb 1983

2nd Printing / 1st Ed Revised =  EP Dutton 1983
§  Changes & corrections in captions marked with * asterisks
§  No changes or additions in pictures.

3rd Printing / 1st Ed Revised (= 3rd revision) = American Malacologist Inc 1986
§  Only one new asterisk added,
§  new table of Errata added to page 411.

Hope this is of help!
Leslie

Paul,
As I understand it, the latest edition is merely a reprint of the 3rd
edition and as such would have the errata originally printed on the last
page of that edition.
Tom
E