  Recently, Grabowska and Kaplan proposed a four-dimensional lattice
formulation of chiral gauge theories on the basis of a chiral overlap operator.
We compute the classical continuum limit of the fermion number anomaly in this
formulation. Unexpectedly, we find that the continuum limit contains a term
which is not Lorentz invariant. The term is, however, proportional to the gauge
anomaly coefficient, and thus the fermion number anomaly in this lattice
formulation automatically restores the Lorentz-invariant form when and only
when the anomaly cancellation condition is met.
