Preheat oven to 350.  Rinse blueberries and drain.  Place in bottom of 10x6 glass baking dish; sprinkle with lemon juice.  Mix next 4 ingredients with a fork until it resembles coarse corn meal   (There will be some lumps in it).  Distribute flour mixture over blueberries; drizzle top with butter.  Combine cinnamon and sugar; sprinkle on top.  Bake 35-40 minutes.  Do not overbake.  Serve with ice cream, coffee cream, or half and half.  Serves 6-8.