  We report the discovery of rapid periodic signals in the light curves of two
cataclysmic variables with prominent white-dwarf components in their spectra,
SDSS J1457+51 and BW Sculptoris. These stars therefore appear to be new members
of the GW Lib class of variable star, in which the fast periodic (and
non-commensurate with the orbital period) signals are believed to arise from
non-radial pulsations in the underlying white dwarf. The power spectra of both
stars show complex signals with primary periods near 10 and 20 minutes. These
signals change in frequency by a few percent on a timescale of weeks or less,
and probably contain an internal fine structure unresolved by our observations.
We also detect double-humped waves signifying the underlying orbital periods,
near 78 minutes for both stars. In addition, BW Scl shows a transient but
powerful signal with a period near 87 minutes, a quiescent superhump. The 11 %
excess over the orbital period is difficult to understand, and may arise from
an eccentric instability near the 2:1 resonance in the accretion disc.
