Semi-Nude Male - Late 19th Century - Unknown Artist

I spotted this very nice academic study several days ago on one of the European eBay sites. Unfortunately the drawing is unsigned so the identity of the artist is lost to the ages! The thing that grabbed my attention and something which really stands out from the usual pose male subjects take is that very masculine pose, arms crossed, legs spread far apart, and a look that challenges the viewer. Pay close attention to the drawing technique and the displayed skill of the artist. Enjoy.