On the left-hand side of the top level of the room with the
buzz-saw robots, if you jump and press attack at the top of
the arc it will open the door to a secret treasure room to
your left. The same holds true in the room with the spear-
throwers and the steel bars across some of the hallways.
Both of these rooms are in the fourth area and you have to
be pretty darn good to be there.