[rfeenstra]

NOT electrolytic.  It is a standard paper/foil capacitor.  The line, as said previously, indicates the connection that is connected to the foil that is on the outside of the rolled foil/paper.  This end of the capacitor is normally connected to the lower impedance to ground in the circuit.  By doing that, the outside foil acts as a shield for the higher impedance side of the circuit, thus reducing the chance of outside interference (hum.)