  The neutron skin and halo distributions in medium and heavy nuclei are
calculated within the extended Thomas-Fermi approximation. Calculations are
carried out for the effective Skyrme-like forces using the direct variational
method. The analytical expression for the isovector shift of the rms radii
$\Delta r_{np}$ as a sum of skin- and halo-like terms is obtained. The
contribution of halo and skin terms to $\Delta r_{np}$ are found to be
approximately equal.
