Idra
meaning a hydra, was the name given to the Testone of Hercules I, Duke of Ferrara (1471-1505), which bears the figure of this fabled monster on the re- verse.
Source: Frey's Dictionary (American Journal of Numismatics, Vol. 50, 1916)
meaning a hydra, was the name given to the Testone of Hercules I, Duke of Ferrara (1471-1505), which bears the figure of this fabled monster on the re- verse.