This is Spicy Mystery Stories for August 1936, cover by H.J. Ward. The ISFDB entry for this issue is here. I checked its dating on the Galactic Central index page. This version of the cover is from Pulp Covers, which also has a very nice clean version of the underlying painting:

According to Pulp covers, this painting sold for $143,400. So check carefully the next time you’re tempted to throw out “junk” from your attic!