Could it be Herbert Williams' 'Portrait Photography' by any chance? I don't have the book, nor can I find an image of the cover online, but it was written in 1937 and the snippet I gleaned from Google Books seemed to fit your criteria. One of the subheadings is "On Posing and Treatment of the Sitter".
Also found along similar lines is Modern Portraiture from you Mr. Stanley Jordan. The only image I found was an ebay listing for a hardcover copy - no image on the cover, however, it does show a couple of pages from inside: