Stratos, Akarnania, AR Hemidrachm, 14mm, 2.45g. 420-400 BC. 

Head of the river-god Acheloos right, crescent below.
Large retrograde F within incuse. 

Traité II-4, 7; BCD Akarnania 2 (this coin); Imhoof Akarnanien 1 (under Oinadae).

With permission of Nomos AG, auction 3, Lot 76, May 2011.
Ex M&M BCD collection sale.
Very rare.