  Let $G$ be a Lie group with a biinvariant metric, not necessarily positive
definite. It is shown that a certain construction carried out in an earlier
paper for the fundamental group of a closed surface may be extended to an
arbitrary infinite orientation preserving cocompact planar discrete group of
euclidean or non-euclidean motions $\pi$ and yields (i) a symplectic structure
on a certain smooth manifold $\Cal M$ containing the space $\roman{Hom}(\pi,G)$
of homomorphisms and, furthermore, (ii) a hamiltonian $G$-action on $\Cal M$
preserving the symplectic structure together with a momentum mapping in such a
way that the reduced space equals the space $\roman{Rep}(\pi,G)$ of
representations. More generally, the construction also applies to certain
spaces of projective representations. For $G$ compact, the resulting spaces of
representations inherit structures of {\it stratified symplectic space\/} in
such a way that the strata have finite symplectic volume . For example, {\smc
Mehta-Seshadri} moduli spaces of semistable holomorphic parabolic bundles with
rational weights or spaces closely related to them arise in this way by {\it
symplectic reduction in finite dimensions\/}.
