  Maximum disk mass models fitted to galaxy rotation curves are used to show
that dark matter (DM) halos in late-type and dwarf spheroidal (dSph) galaxies
satisfy well defined scaling laws. Halos in less luminous galaxies have smaller
core radii, higher central densities, and smaller central velocity dispersions.
Implications: (1) A single, continuous physical sequence of increasing mass
extends from the tiniest dSphs to the most luminous spirals. (2) The high DM
densities in dSph galaxies are normal for such dwarf galaxies. Since virialized
density depends on collapse redshift z, the smallest dwarfs formed about delta
z = 7 earlier than the biggest spirals. (3) The high DM densities of dSphs
implies that they are real galaxies formed from primordial density
fluctuations. They are not tidal fragments. (4) Because dwarf galaxies become
more numerous and more nearly dominated by DM as luminosity decreases, there
may be a large population of objects that are completely dark. Such objects are
a canonical prediction of cold DM theory. (5) The slopes of the DM parameter
correlations provide a measure on galactic mass scales of the slope n of the
power spectrum of primordial density fluctuations. Our results not yet
corrected for baryonic compression of DM give n = -1.9 +- 0.2. This is
consistent with cold DM theory.
