We explicitly determine the symplectic structure on the phase space of Chern-Simons theory with gauge group G ⋉ g on a three-manifold of topology R× S g,n, where S ∞ g,n is a surface of genus g with n + 1 punctures. At each puncture additional variables are introduced and coupled minimally to the Chern-Simons gauge field. The first n punctures are treated in the usual way and the additional var...