PRIVATE DETECTIVE STORIES was a long-running pulp, lasting for a total of 134 issues from June 1937 through December 1950.  The last 11 issues, beginning with the September 1949 issue, appeared under the title PRIVATE DETECTIVE.  PRIVATE DETECTIVE STORIES was a companion to SPICY DETECTIVE STORIES, both being published by Frank Armer.  Compared to its sister publication though, PRIVATE DETECTIVE was a bit more restrained on the sex angle, both in terms of its art and its stories.