My original tumblr post was here. This image was first posted on tumblr by damsellover, who includes the date “March 1962.” This pulp cover contains the text “Shock Mystery Tales. Satan’s Mistress, by Craighton Lamont. Soft Hands of Madness, by Bill Ryder. Horror Island, by Anthony Stuart.” I have been unable to determine the artist, but did find a slightly larger version of the cover image at pulpcovers.com.