Limbless locomotion reveals increasing interest among locomotion methods inspiring mobile robots. This paper deals with the lateral undulation, one type of terrestrial snakelike locomotion. It represents the first part of a research project based on a biologically inspired approach. The purpose, in this first place, is to cover the physical principles involved in lateral undulation. Following an overview of the lateral undulation as it occurs in nature, the authors consider a generic planar mechanism and a related environment that suit to satisfy the fundamental mechanical phenomenon observed in the locomotion of terrestrial snakes. Application of a relatively simple control law is tested through dynamic simulations. In the second place, the results of this introductory study are going to be used in the research of an appropriate technological solution for an artificial snake exerting lateral undulation. The approach presented differs from other works on the subject in the sense that it does not require any wheeled structure.