Let (Y, , t ) be a locally compact dynamical system, where the , t denotes a continuous, one parameter semigroup of maps on Y. When each , t is a homeomorphism, a nonselfadjoint crossed product algebra is defined as the subalgebra of the C*-crossed product C 0 (Y ) < R supported on t>0; when each , t is only continuous, the crossed product C 0 (Y ) < R + can still be defined. The ideal structure of such an algebra is determined in the case where the semigroup action is the suspension of a discrete, free action on a smaller space X. A generalization of Effros Hahn is given, whereby one may find a meet-irreducible ideal over any arc closure in Y. The meet-irreducible ideals form a topological space in the hullkernel topology, and there is a one-to-one correspondence between closed sets in this space and closed ideals in the algebra. A subset of this space is homeomorphic to the space of finite arcs in the subarc topology. The irrational flow algebra is considered as a special case.