The corotating convection model invokes a systematic large-scale pattern of plasma motion through the Jovian magnetosphere, a pattern fixed in corotating (System III) coordinates and established by an observed longitudinal asymmetry of the S+ ion distribution in the inner Io torus. In its various versions published to date, the corotating convection model would preserve this longitudinal asymmetry throughout the magnetospheric convection system; the model is thus in conflict with the high degree of longitudinal symmetry that is observed to exist in the hot outer Io torus and presumed to exist also in the magentosphere outside the torus region, representing the corotation lag associated with ion production and charge exchange in the Io torus. We propose to solve this difficulty by superimposing on the corotating convection system a strong retrograde flow confined to the torus. The addition of this azimuthal flow in the torus region renders the plasma density distribution almost symmetric with respect to longitude in the outer torus and beyond (as required by direct observation), while retaining a corotating convection pattern outside the torus (whose existence is supported indirectly by a number of observations). Serendipitously, the condition of approximate azimuthal symmetry of the plasma density distribution permits an analytic solution of the otherwise intractable equations governing the corotating convection pattern. ¿ American Geophysical Union 1987