The system of the multicellular animals presented here is an alternative to the traditional classification which still operates with the categories of Carl v. Linné, including typological divisions in artificial species groups. In a new approach to the phylogenetic order in nature this book strives for an objective systematisation of the Metazoa. It seeks a new path in the field of research and academic teaching based on the theory and methodology of phylogenetic systematics. This third volume covers the Metazoa from the Nemathelminthes to the Mammalia.