In the present series of papers, the post-cranial muscles of Psammophis sibilans are dealt with according to their position between connective tissue septa radiating from the vertebral column to the inner side of the skin. Four of those septa are present and are numbered CS1,2,3 & 4 respectively. In general, the muscles of the snake in question which are homologous with those of lizards are numbered following the same system of nomenclature of KHALIL, et al. (1977), while muscles which have no homolgues in lizards were given new numbers preceded by op letters (ophidian). The first group of muscles enclosed between the first and second connective tissue septa (CS1 & CS2) are: cranio-spinal (1), inner semispinal (2), outer semispi nal (15) and intervertebral (op la & b).