  Deep HST/WFPC2 (V,I) photometry is used to investigate the globular cluster
system (GCS) in NGC 4874, the central cD galaxy of the Coma cluster. The
luminosity function of the clusters displays its normal Gaussian-like shape and
turnover level. Other features of the system are surprising: the GCS is (a)
spatially extended, with core radius r_c = 22 kpc, (b) entirely metal-poor (a
narrow, unimodal metallicity distribution with mean [Fe/H] = -1.5), and (c)
modestly populated, with specific frequency S_N = 3.7 +- 0.5. We suggest on the
basis of some simple models that as much as half of this galaxy might have
accreted from low-mass satellites, but no single one of the three classic modes
of galaxy formation (accretion, disk mergers, in situ formation) can supply a
fully satisfactory formation picture. Even when they are used in combination,
strong challenges to these models remain. The principal anomaly in this GCS is
essentially the complete lack of metal-rich clusters. If these were present in
normal (M87-like) numbers in addition to the metal-poor ones that are already
there, then the GCS in total would more closely resemble what we see in many
other giant E galaxies.
