  Long lived modes of elliptical galaxies can exist {\it \`a la} van Kampen.
Specific systems may possess long lived oscillations which Landau damp on time
scales longer than a Hubble time. Some physical processes such as a close
encounter, tidal forces from a cluster or an orbiting satellite could
preferentially excite a coherent mode. These may relate to the observed faint
structure in elliptical galaxies such as shells and ripples. Their detection in
projected phase space would ultimately provide a detailed probe of the
underlying potential. I give an overview of linear perturbations to stationary
solutions of the Vlasov equation, including a discretized Hermite polynomial
expansion which explicitly demonstrates completeness and orthogonality of
solutions. Some exact solutions are shown, which implies the feasibility of
such a procedure and suggest future fully numerical studies.
