  We derive a semiclassical scheme for the conductance through a rectangular
cavity. The transmission amplitudes are expressed as a sum over families of
trajectories rather than a sum over isolated trajectories. The contributing
families are obtained from the evaluation of a finite number of continued
fractions. We find that, contrary to the chaotic case, the conductance
fluctuations increase with the incoming energy and the correlation function
exhibits a singularity at the origin.
