Pluto was the ruler of the underworld in classical mythology. The earlier name for the god was Hades, which became more common as the name of the underworld as a place. In ancient Greek religion and myth, Pluto represents a more positive concept of the god who presides over the afterlife. Pluto and Hades differ in character, but they are not distinct figures and share their two major myths. In Greek cosmogony, the god received the rule of the underworld in a three way division of sovereignty over the world, with his brothers Zeus ruling Heaven and Poseidon the Sea. Pluto (genitive Plutonis) is the Latinized form of the Greek Plouton. Pluto's Roman equivalent is Dis Pater. Under the name Pluto, the god appears in other myths in a secondary role, mostly as the possessor of a quest-object, and especially in the descent of Orpheus or other heroes to the underworld. Cerberus in Greek and Roman mythology, is a multi-headed (usually three-headed) dog, or hellhound with a serpent's tail, a mane of snakes, and a lion's claws. He guards the entrance of the underworld to prevent the dead from escaping and the living from entering.