The Voyager-1 and 2 outbound observations of periodic double-peak flux maxima (which mark encounters with the magnetodisc) are separated into two distinct branches - a ''leading'' branch (N→S disc crossings) and a ''trailing'' branch (S→N disc crossings). On a plot of System III (1965.0) longitude vs, radial distance, the leading branch has a positiv slope (~1.2¿/RJ) and the trailing branch has a relatively flat slope (~0.3¿/RJ). The two branches meet at ~80--100 RJ, beyond which periodic single peak or closely-spaced multiple peaks are generally observed. This paper examines this structure using the 3 principal disc models which have emerged to expalin periodicities in the Jovian magnetospheres: (1) the rigid magnetodisc model, (2) the bent or warped magnetodisc model, and (3) the wavy magnetofisc model. The rigid disc model does not allow for the merging of the double-peak structure into a single-peak structure, and the bent disc model cannot explain the phase lag of the leading peaks. Both the merging of the peaks and the phase asymmetry can be explained by a wavy-disc model in which the wave amplitude is fixed. The disc surface is then described in Jovigraphic cylindrical coordinates by z=-r0 tan &agr; cos [ϕ+&OHgr; (r-r0) /V0> where r0?20 RJ, &agr;?10.7¿ is the dipole axis tilt angle, &OHgr;=2&pgr;/10 hr-1 is the angular speed of Jupiter's rotation, and V0?40 RJ/hr is the speed of wave propagation. Count rate profiles along the Voyager trajectories may then be reproduced using a simple model in which the rates vary exponentially in radial distance and Δz, the distance from the disc surface.