  We present measurements of the CaII triplet and the Ca4227 Lick-index for a
sample of early-type galaxies in the Coma cluster, deriving, for the first
time, their corresponding relationships with velocity dispersion. Compared with
a similar subsample of ellipticals in the field, Coma galaxies with velocity
dispersions in the range ~ 180-270 km/s exhibit significant differences in the
strengths of the Ca features, suggesting an influence of the environment on the
star formation histories of these galaxies. We argue that the main scenarios
previously proposed to explain the relatively low CaII triplet of galaxies are
not able by themselves to simultaneously reconcile the strengths of the two Ca
indices in both environments.
