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Four-wave-mixing signals from excitons under linear-circular polarized excitation exhibit an elliptical polarization, depending on both the pulse delay and the spectral position. Besides the resonances corresponding to excitons and exciton-biexciton transitions, a breakup of the exciton line is found reflecting the influence of correlations on the four-point level. An analysis accounting for the exciton density, the bound biexciton, and the exciton-exciton scattering continuum reveals that these features are not due to an antibound two-exciton state. Instead, they result from an interference of the correlated exciton continuum with the exciton density. In addition, the modeling shows that the signals ellipticity is highly sensitive to the influences of different correlations and, therefore, allows for a discrimination of their contributions. [S0031-9007(98)08064-8] PACS numbers: 71.35. Gg, 42.50.Md, Quantum kinetic effects have a key role in revealing the quantum nature of the matter light interaction. Therefore, the search for distinct experimental fingerprints of correlated quantum kinetics beyond the scope of the Boltzmann equation or time-dependent Hartree-Fock theory has attracted much attention in recent years [1][2][3][4][5][6][7]. So far, firm evidence for phonon quantum kinetics has been found by demonstrating the occurrence and the controllability [2] of phonon sidebands and by a demonstration of the limits imposed by the energy-time uncertainty [4,5]. Also for the case of Coulomb quantum kinetics in the high excitation regime specific predictions have been made [7], namely, that time-resolved four-wave-mixing (FWM) spectra should show a sideband having a frequency which scales with the plasma frequency. However, this prediction has not been experimentally verified up to now.The dynamics of biexcitonic contributions to FWM on the other hand is a prominent example related to Coulomb quantum kinetics at moderate excitation densities [8][9][10][11][12][13][14]. Recently, the dependence of the exciton-exciton correlation in the scattering state continuum on a magnetic field has been investigated [11]. In this Letter we demonstrate that even for moderate excitation the correlated Coulomb quantum kinetics leads to significant effects the description of which requires one to go beyond the coherent limit. In particular, the combined dynamics of the correlated two-pair scattering continuum and exciton densities, the latter having lost their interband coherence, leads to characteristic spectral signatures of the polarization state of FWM signals. The almost perfect agreement between calculated and experimental data obtained from ZnSe quantum wells allows one to draw a conclusive picture of the processes relevant for the signal generation.Spectrally resolved degenerate FWM experiments are performed on a 7.5 nm thin ZnSe͞ZnS 0.06 Se 0.94 singlequantum-well sample grown by molecular-beam epitaxy lattice matched to subsequently removed GaAs substrates. The exciton binding energy amounts to 20 meV. Pulses from a frequ...