  We have obtained Keck Low Resolution Imaging Spectrograph images in V and I
of the newly discovered Local Group dwarf galaxies Pegasus dSph and Cassiopeia
dSph and their surrounding field. The first stellar luminosity functions and
color-magnitude diagrams are presented for stars with V <~ 25 and I <~ 24. The
distances to the new dwarfs are estimated from the apparent I mag of the tip of
the red giant branch to be: D_MW (Peg dSph) = 830 +/- 80 kpc and D_MW (Cas
dSph) = 760 +/- 70 kpc, consistent with their belonging to the extended M31
satellite system. Both galaxies are dwarf spheroidals (dSphs) with red giant
branch morphologies indicating predominantly old stellar populations and
estimated mean metallicities, <[Fe/H]>, of -1.3 +/- 0.3 for Peg dSph and -1.4
+/- 0.3 for Cas dSph. Their central surface brightness-<[Fe/H]>-absolute
magnitude relationship follows that of other Local Group dSphs, dwarf
ellipticals, and dwarf irregulars. In contrast to four out of nine Milky Way
dSphs (the four that lie beyond D_MW =100 kpc), none of the six known M31 dSphs
appears to have a dominant intermediate-age population.
