  We show that the two-dimensional metallic state in Si-MOS samples persists
over a wide range of temperatures (16 mK to 8 K), sample peak mobilities
(varying by a factor of 8), carrier densities (0.8 to $35\times 10^{11}$
cm$^{-2}$) and conductances from 0.3 to $120 e^2/h$. Our data reveal a failure
of the universal one-parameter scaling. We have found a weak delocalizing
logarithmic correction to the conductivity, which governs a weak increase in
the conductivity of the 2D metal as $T$ approaches zero.
