Tarsos in Cilicia, 211-217 AD., Caracalla, Cornell 116.

Tarsos in Cilicia, Caracalla, 211-217 AD.,
Æ32 (32-33 mm / 16,17 g),
Obv.: [AVT KAI M AVP CЄV]HPOC ANTΩN[ЄINOC CЄB] / Π - Π (across field), laureate head of Caracalla left.
Rev.: Herakles and the Lernaean hydra: ..ANH - CЄ.. / ЄK (uncertain legend around and in lower field) / TAPCOV (in exergue), Herakles standing left, nude, holding lion's skin on left arm and raising club far over his right shoulder, about to beat to death the Hydra.
SNG Levante - ; SNG Levante Suppl. - ; SNG France - ; SNG von Aulock - ; R. Bräuer, "Die Heraklestaten auf antiken Münzen," ZfN 28 (1910), pl. 2, 12 ; Voegtli 2q ; Cornell 116 .
cf. http://www.coinarchives.com/a/lotviewer.php?LotID=139892&AucID=166&Lot=6881

The second labour of Hercules, the Lernaean Hydra

In Greek mythology, the Lernaean Hydra was an ancient nameless serpent-like chthonic water beast that possessed numerous heads— the poets mention more heads than the vase-painters could paint— and poisonous breath. The Hydra of Lerna was killed by Hercules as one of his Twelve Labours. Its lair was the lake of Lerna in the Argolid, though archaeology has borne out the myth that the sacred site was older even than the Mycenaean city of Argos, for Lerna was the site of the myth of the Danaids. Beneath the waters was an entrance to the Underworld, and the Hydra was its guardian.
The Hydra was the offspring of Typhon and Echidna, noisome offspring of the earth goddess, Gaia. It was said to be the sibling of the Nemean Lion, the Chimaera and Cerberus.

The second labour of Hercules: Upon reaching the swamp near Lake Lerna, where the Hydra dwelt, Hercules covered his mouth and nose with a cloth to protect himself from the poisonous fumes and fired flaming arrows into its lair, the spring of Amymone, to draw it out. He then confronted it, wielding a harvesting sickle in some early vase-paintings; Ruck and Staples have pointed out that the chthonic creature's reaction was botanical: upon cutting off each of its heads he found that two grew back, an expression of the hopelessness of such a struggle for any but the hero, Hercules.
Realising that he could not defeat the Hydra in this way, Hercules called on his nephew Iolaus for help. His nephew then came upon the idea (possibly inspired by Athena) of using a burning firebrand to scorch the neck stumps after decapitation, and handed him the blazing brand. Hercules cut off each head and Iolaus burned the open stump leaving the hydra dead; its one immortal head Hercules placed under a great rock on the sacred way between Lerna and Elaius, and dipped his arrows in the Hydra's poisonous blood, and so his second task was complete. The alternative to this is that after cutting off one head he dipped his sword in it and used its venom to burn each head so it couldn't grow back.
Hercules later used an arrow dipped in the Hydra's poisonous blood to kill the centaur Nessus; and Nessus's tainted blood applied to the Tunic of Nessus.
When Eurystheus, the agent of ancient Hera who was assigning to Hercules The Twelve Labours, found out that it was Hercules' nephew who had handed him the firebrand, he declared that the labour had not been completed alone and as a result did not count towards the ten labours set for him. The mythic element is an equivocating attempt to resolve the submerged conflict between an ancient ten Labours and a more recent twelve.

Near Argos, the former presence of a large freshwater lagoon, named Lake Lerna, has been deduced from subsurface deposits. The lake was separated from the open sea by a beach barrier. It originated when the postglacial sea level rise reached its culmination point and extended over a diameter of 4.7 km in the Early Bronze Age. Increased soil erosion then caused a rapid silting, but remnants of Lake Lerna persisted until the last century. Anthropological studies have shown how the inhabitants of this coastal marsh have suffered from malaria in the past. It may be that the story of the legendary fight between Herakles and the Lernaean Hydra reflects the struggle of the Lanai people as they tried to change the inhospitable environment by draining the lake. (Eberhard Zangger: "Prehistoric Coastal Environments in Greece: The Vanished Landscapes of Dimini Bay and Lake Lerna", Journal of Field Archaeology 18 (1991) 1--15)

Modern geological techniques such as core drilling have identified the site of the vanished sacred Lake Lerna, which was a freshwater lagoon, separated by barrier dunes from the Aegean. In the Early Bronze Age Lake Lerna had an estimated diameter of 4.7 km. Deforestation increased the rate of silt deposits and the lake became a malarial marsh, of which the last remnants were drained in the nineteenth century.