  Prompted by the discovery of the accreted Canis Major dwarf galaxy and its
associated globular cluster (GC) system (Martin etal.), we investigate the
contribution of accreted GCs to the Galactic system. The Canis Major GCs, and
those associated with the Sagittarius dwarf galaxy, exhibit a range of
galactocentric radii, prograde and retrograde motions, and horizontal branch
morphologies, indicating that such properties are of limited use in identifying
accreted GCs. By contrast, we find that the age-metallicity relation (AMR) of
these dwarf galaxies is distinct from that of the main Galactic GC distribution
at intermediate-to-high metallicities ([Fe/H] > -1.3). The accretion of GCs
with a distinct AMR would explain much of the apparent age spread in the
Galactic GC system. The Canis Major and Sagittarius AMRs are similar to those
of other Local Group dwarf galaxies and are consistent with a simple closed-box
chemical enrichment model -- a further indication that these GCs formed outside
of the Milky Way. The Canis Major GCs all have smaller-than-average sizes for
their galactocentric distances, lending further support to their origin outside
of the Milky Way. Our findings suggest that accretion of similar mass dwarfs
does not appear to have played a major role in building the stellar mass of the
thick disk or bulge of the Milky Way.
