  We combine the results from several HST investigations of the central
structure of early-type galaxies to generate a large sample of parameterized
surface photometry. The studies included were those that used the "Nuker law"
to characterize the inner light distributions of the galaxies. The sample
comprises WFPC1 and WFPC2 V band observations published earlier by our group, R
band WFPC2 photometry of Rest et al., NICMOS H band photometry by Ravindranath
et al. and Quillen et al., and the BCG WFPC2 I band photometry of Laine et al.
The distribution of the logarithmic slopes of the central profiles strongly
affirms that the central structure of elliptical galaxies with Mv < -19 is
bimodal, based on both parametric and non-parametric analysis. At the HST
resolution limit, most galaxies are either power-law systems, which have steep
cusps in surface brightness, or core systems, which have shallow cusps interior
to a steeper envelope brightness distribution. A rapid transition between the
two forms occurs over the luminosity range -22 < Mv < -20, with cores
dominating at the highest luminosities, and power-laws at the lowest. There are
a few "intermediate" systems that have both cusp slopes and total luminosities
that fall within the core/power-law transition, but they are rare and do not
fill in the overall bimodal distribution of cusp slopes. These results are
inconsistent with the Ferrarese et al. Virgo Cluster Survey (VCS) analysis.
However, using galaxies common to the VCS samples, we demonstrate that the VCS
models of the cusps are either a poor match to the observations or consist of
forms fitted to the galaxy envelopes and extrapolated inward to the HST
resolution limit.
