Zero-field-cooled (ZFC) and field-cooled (FC) magnetization data for fields applied parallel and perpendicular to the plane of flat superconducting Pb discs (Tc=7.2 K) are presented. A quasi-irreversibility temperature T*, which differs for the two orientations, can be identified in these data. T* is found to vary with the field approximately as (1-T*/Tc)H1.085. © 1991 The American Physical Society.