Copyright 1941 by Comic Magazines, Inc.
The on-sale date is from the publication date recorded in the Catalog of Copyright Entries, Part 2, Periodicals, 1942, New Series, Vol. 37, No. 2.
All Gustavson credits verified and courtesy of Terry Gustafson, son of Paul Gustavson.
Last appearance. There is a blurb at the end of the story that there will be more Madam Fatal next issue, but there wasn't.