Central Italy, ca. 100-30 BC., "Italo-Baetican" type, Æ 16, Stannard, Series 1a.

Central Italy, "Italo-Baetican" type, ca. 100-30 BC.,
Æ 16 (15-16 mm / 7,44 g), bronze, axes irregular alignment ↑↗ (ca. 40°),
Obv.: Geryon, with six arms and six legs, advancing right, helmeted, cuirassed, holding a shield before him, and brandishing spears; [border of dots?].
Rev.: Hercules fighting the Hydra right, a club in his raised right hand; linear border.
cf. Clive Stannard "The Local Coinages of Central Italy in the Late Roman Republic" , Provisional Catalogue, October 2007, Series 1a ; Clive Stannard, Iconographic parallels between the local coinages of central Italy and Baetica in the first century BC, Acta Numismática 25 (1995), 21 ; Overstrikes and imitative coinages in central Italy in the late Republic, Essays Hersh 209ff. .

In Greek mythology, Geryon (Greek: Γηρυών; genitive: Γηρυόνος) son of Chrysaor and Callirrhoe and grandson of Medusa, was a fearsome giant who dwelt on the island Erytheia of the mythic Hesperides in the far west of the Mediterranean. A more literal-minded later generation of Greeks associated the region with Tartessos in southern Iberia.
Geryon was often described as a monster with human faces. According to Hesiod Geryon had one body and three heads, whereas the tradition followed by Aeschylus gave him three bodies. A lost description by Stesichoros said that he has six hands and six feet and is winged; there are some mid-sixth-century Chalcidian vases portraying Geryon as winged. Some accounts state that he had six legs as well while others state that the three bodies were joined to one pair of legs. Apart from these bizarre features, his appearance was that of a warrior. He owned a two-headed hound named Orthrus, which was the brother of Cerberus, and a herd of magnificent red cattle that were guarded by Orthrus, and a herder Eurytion, son of Erytheia.

In the fullest account in the Bibliotheke of Pseudo-Apollodoros, Heracles was required to travel to Erytheia, in order to obtain the Cattle of Geryon as his tenth labour. On the way there, he crossed the Libyan desert and became so frustrated at the heat that he shot an arrow at Helios, the Sun. Helios "in admiration of his courage" gave Heracles the golden cup he used to sail across the sea from west to east each night. Heracles used it to reach Erytheia, a favorite motif of the vase-painters. Such a magical conveyance undercuts any literal geography for Erytheia, the "red island" of the sunset.
When Heracles reached Erytheia, no sooner had he landed than he was confronted by the two-headed dog, Orthrus. With one huge blow from his olive-wood club, Heracles killed the watchdog. Eurytion the herdsman came to assist Orthrus, but Heracles dealt with him the same way.
On hearing the commotion, Geryon sprang into action, carrying three shields, three spears, and wearing three helmets. He pursued Heracles at the River Anthemus but fell victim to an arrow that had been dipped in the venomous blood of the Lernaean Hydra, shot so forcefully by Heracles that it pierced Geryon's forehead, "and Geryon bent his neck over to one side, like a poppy that spoils its delicate shapes, shedding its petals all at once". Heracles then had to herd the cattle back to Eurystheus.

In Roman versions of the narrative, on the Aventine hill in Italy, Cacus stole some of the cattle as Heracles slept, making the cattle walk backwards so that they left no trail, a repetition of the trick of the young Hermes. According to some versions, Heracles drove his remaining cattle past a cave, where Cacus had hidden the stolen animals, and they began calling out to each other. In others, Caca, Cacus' sister, told Heracles where he was. Heracles then killed Cacus, and according to the Romans, founded an altar where the Forum Boarium, the cattle market, was later held.
To annoy Heracles, Hera sent a gadfly to bite the cattle, irritate them and scatter them. The hero was within a year able to retrieve them. Hera then sent a flood which raised the level of a river so much, Heracles could not cross with the cattle. He piled stones into the river to make the water shallower. When he finally reached the court of Eurystheus, the cattle were sacrificed to Hera.

In the Aeneid, Vergil may have based the triple-souled figure of Erulus, king of Praeneste, on Geryon. The Herculean Sarcophagus of Genzano features a three headed representation of Geryon.