The allocortex has just three or four layers of neuronal cell bodies in contrast to the six layers of the neocortex. There are three subtypes of allocortex, the paleocortex, archicortex and periallocortex. Paleocortex is a type of thin, primitive cortical tissue that consists of three cortical laminae (layers of neuronal cell bodies). The two granular layers II and IV of neocortex are absent in paleocortex. The main areas of paleocortex are the olfactory bulb, olfactory tubercle and piriform cortex. Archicortex is a type of cortical tissue that consists of four laminae (layers of neuronal cell bodies). The main areas of archicortex are the hippocampus and dentate gyrus.