  We have studied the magnetic excitations in Ca$_{2-x}$Sr$_x$RuO$_4$, x=0.52
and 0.62, which exhibit an anomalous high susceptibility and heavy mass Fermi
liquid behavior. Our inelastic neutron scattering experiments reveal strongly
enhanced magnetic fluctuations around an incommensurate wave vector (0.22,0,0)
pointing to a magnetic instability. The magnetic fluctuations show no
correlation in c-direction and also along the RuO$_2$-planes the signal is
extremely broad, $\Delta q =0.45$ \AA$^{-1}$. These fluctuations can
quantitatively account for the high specific heat coefficient and relate to the
high macroscopic susceptibility. The magnetic scattering is attributed to the
$\gamma$-band, the active band for spin triplet superconductivity in
Sr$_2$RuO$_4$.
