Topographic division ( Swanson & Bota, 2010 ) : A macrostructural part of the nervous system (Monro, 1783) created at least conceptually by cutting (dividing) with a knife between defined structural landmarks and fitting into a recognized macrostructural hierarchy; see Swanson (2000). The central nervous system (Meckel, 1817) and peripheral nervous system (Meckel, 1817) are the two major topographic divisions, except in animals with just a nerve net, which has divisionless topography.