the god of the infernal regions, was the same as Pluto, and so called from the Greek word ὁρκός, signifying a tomb or sepulchre; or from ὁρκός, an oath sworn by the river Styx. The ancients gave this name to all the divinities of the infernal regions, even to Cerberus. There was a river of the same name in Thessaly, which took its rise in the marshes of the Styx, and the waters of which were so sick that they floated like oil upon the surface of the river Penus, into which they discharged themselves. This probably suggested to the poets the idea of the infernal Ordeal abodes, which they denominated Orcus. Orcus has been confounded with Charon. He had a temple at Rome.