We construct an effective Lagrangian for the hadronic decays of a heavy
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 mass
spectra in the charmonium and
bottomonium systems can be obtained within this framework. The mass
dependence of the various terms in the Lagrangian is discussed on the
basis of a quark model.