Watch List notes:

GREEK COINS
PHOKIS

Delphi. Amphictionic issues, circa 336-334 BC. Hemidrachm (Silver, 14mm, 2.94 g 1). Veiled head of Demeter to left, wearing wreath of grain leaves. Rev. ΑΜΦΙΚΤ - ΙΟΝΩΝ Serpent coiled to right around omphalos covered by a net of woolen cords. BCD 389. SNG Berry 585. Of great rarity, one of only four known examples. Slightly rough surfaces and faint traces of overstriking, otherwise, good very fine.

From a European collection, formed before 2005.
For a rapturous description of how rare this little coin is, see the commentary to BCD 389.