  The zero-field temperature-dependence of the resistivity of two-dimensional
holes are observed to exhibit two qualitatively different characteristics for a
fixed carrier density for which only the metallic behavior of the so-called
metal-insulator transition is anticipated. As $T$ is lowered from 150 mK to 0.5
mK, the sign of the derivative of the resistivity with respect to $T$ changes
from being positive to negative when the temperature is lowered below $\sim$30
mK and the resistivity continuously rises with cooling down to 0.5 mK,
suggesting a crossover from being metal-like to insulator-like.
