We construct an effective Lagrangian for the hadronic decays of a heav
y excited s-wave-spin-one quarkonium Psi' into a lower s-wave-spin-one
state Psi. We show that reasonable fits to the measured invariant mas
s spectra in the charmonium and bottomonium systems can be obtained wi
thin this framework. The mass dependence of the various terms in the L
agrangian is discussed on the basis of a quark model.