Pre-1978 no mark. The item has no copyright marks on it as can be seen at links and original upload. At bottom left are logos for First National and Continental Litho Company--they printed the poster. At bottom right is a number which probably relates to the print job for the poster.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (50 p.m.a.), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.
{{Information |Description=Poster for the 1931 film ''The Lady Who Dared''. |Source=[http://poster.scancollections.com/view.php?id=443553 source] |Date=[http://www.imdb.com/title/tt0022047/ 1931] |Author=First National Pictures |Permission=Pre-1978 no...