Earthenware vase representing the face of the river god Achelous, dating
to the VI century B.C. and now in the Smith College Museum of Art, Northampton,
MA, USA. Achelous is the main river in Greece and was personified as
a divine being with theranthropic traits, regarded as a son of the primordial
divinities Oceanus and Tethys. The river god came into conflict with
Heracles to win the hand of Deianira, but was defeated and the girl
married the hero. During the fight, Achelous demonstrated his power
of transformation, taking the shape of a serpent and a bull, but was
at last vanquished by Heracles, who took off one of his horns. According
to the version reported by Ovid (Metamorphoses, IX, 85-88),
the horn caught from the river god was changed, by the Naiads, the river
nymphs, into the horn of plenty or cornucopia.
[Source: http://library.artstor.org/library/]