The theory of the boundary behavior in the prime ends for the mappings with finite distortion has been developed in [1] and [2] for the plane domains and in [3] for the spatial domains. The pointwise boundary behavior of the mappings with finite distortion in regular domains on Riemann surfaces was recently studied by us in [4]. Moreover, the problem was investigated in regular domains on the Riemann manifolds for 3 n as well as in metric spaces, see, e.g., [5]. For basic definitions and notations, discussions, and historic comments in the mapping theory on Riemann surfaces, see our previous papers [4,6,7].1. Definition of the prime ends and preliminary remarks. We act similarly to Carathéodory under the definition of the prime ends of domains on a Riemann surface S , see Chapter 9 in [8]. First of all, recall that a continuous mapping :We also use the notations , σ σ , and ∂σ for ( ), (