  We measure the central values (within Re/8) of the CaII triplet line indices
CaT* and CaT and the Paschen index PaT at 8600 AA for a 93%-complete sample of
75 nearby early-type galaxies with BT<12 and Vgal<2490 km/s. We find that the
values of CaT* are constant to within 5% over the range of central velocity
dispersions 100<sigma<340 km/s, while the PaT (and CaT) values are mildly
anti-correlated with sigma. Using simple and composite stellar population
models, we show that: a) The measured CaT* and CaT are lower than expected from
simple stellar population models (SSPs) with Salpeter initial mass functions
(IMFs) and with metallicities and ages derived from optical Lick (Fe, Mg and
Hbeta) indices. Uncertainties in the calibration, the fitting functions and the
SSP modeling taken separately cannot explain the discrepancy. On the average,
the observed PaT values are within the range allowed by the models and the
large uncertainties in the fitting functions. b) The steepening of the IMF at
low masses required to lower the CaT* and CaT indices to the observed values is
incompatible with the measured FeH index at 9916 AA and the dynamical
mass-to-light ratios of ellipticals. c) Composite stellar populations with a
low-metallicity component reduce the disagreement, but rather artificial
metallicity distributions are needed. Another explanation may be that calcium
is indeed underabundant in ellipticals.
