This Letter presents circular polarimetry that unequivocally identifies EXO 033319-2554.2 as only the third eclipsing AM Her star and brings the total number of AM Her stars now identified to 14. The orbital period is 126.4 minutes, as previously reported, and defines a new short-period edge to the period gap seen in all classes of cataclysmic variable stars. EXO 033319-2554.2 shows 2.5 mag deep eclipses of the predominantly accreting magnetic pole on the white dwarf. Before the eclipse, the pole rotates into the line of sight and shows white-light circular polarization, due to cyclotron radiation, that reaches values as high as 10 percent. There is some evidence that the second pole is emitting cyclotron radiation too. How high time resolution photometry, linear polarimetry, and spectroscopy will be of great value in understanding this system.