  The purpose of this paper is to make a further contribution to the Mackey
bijection for a complex reductive group G, between the tempered dual of G and
the unitary dual of the associated Cartan motion group. We shall construct an
embedding of the C*-algebra of the motion group into the reduced C*-algebra of
G, and use it to characterize the continuous field of reduced group C*-algebras
that is associated to the Mackey bijection. We shall also obtain a new
characterization of the Mackey bijection using the same embedding.
