  As in conventional ferromagnets, the Hall resistivity rho_xy of a
La_{2/3}(Ca,Pb)_{1/3}MnO_3 single crystal exhibits both ordinary and anomalous
contributions at low temperature. However, these contributions, unexpectedly,
have opposite signs. Near Tc, the ordinary contribution is no longer evident
and rho_xy is solely determined by the sample magnetization, reaching an
extremum at approximately 40% of the saturated magnetization. A new model for
the anomalous Hall effect, incorporating the quantal phase accumulated by
double-exchange, three-site hopping reproduces this result. Below Tc, rho_xy
reflects the competition between normal and anomalous Hall effects.
