  We study Anderson localization in quasi--one--dimensional disordered wires
within the framework of the replica $\sigma$--model. Applying a semiclassical
approach (geodesic action plus Gaussian fluctuations) recently introduced
within the context of supersymmetry by Lamacraft, Simons and Zirnbauer
\cite{LSZ}, we compute the {\em exact} density of transmission matrix
eigenvalues of superconducting wires (of symmetry class $C$I.) For the unitary
class of metallic systems (class $A$) we are able to obtain the density
function, save for its large transmission tail.
