The term area 30 refers to one of two parts of the architectonically defined retrosplenial cortex in the human and macaque. It is variously considered dysgranular cortex ( Vogt-2012 ) or agranular cortex ( Zilles-2012 ).The other is area 29, which is indisputedly granular cortex. The two are narrow bands aligned side by side in the banks of the posterior cingulate gyrus and isthmus of the cingulate gyrus. The inner band of the two, area 29, is separated from the splenium of the corpus callosum by the callosal sulcus. Externally area 30 is bounded by area 23 ( Vogt-2012 ).. In rodents the area equivalent to area 30 of primates is called the retrosplenial dysgranular area ( Paxinos-2009b ) or dorsal part of the retrosplenial area ( Swanson-2004 ). It is located on the mesial surface of the cerebral hemisphere external to the retrosplenial granular cortex...dorsal and caudal to the splenium of the corpus callosum. Some authors have shown a small 'retrosplenial area, lateral agranular part' in the rat ( Swanson-2004), and mouse ( Dong-2004 ).