Tetradrachm (coin equivalent to four drachmae), coined in Gela, Sicily,
in 460 B.C. and now in the Staatliche Münzsammlung, Munich, Germany.
The image of the bull with a human head represents the river god Gela,
from whom the Sicilian city took its name. In ancient Greece the river
deities were regarded as fearful and dangerous beings, which should
be propitiated with sacrifices and were frequently depicted as therianthropic
beings. The main river in Greece was the Achelous, son of Oceanus and
Tethys, who was generally represented as a bull with a human face. In
the Iliad, the Scamander river is described as a being “with a
human face”, against which the valiant warrior Achilles fought.
To this river the Trojans sacrificed living bulls and horses, which
were thrown into its whirlpools (Iliad, XXI, 131-132).
[Source:
http://commons.wikimedia.org/wiki/File:Gela,_tetradracma,_460_ac._ca.JPG]