Thrace, Byzantion AR Hemidrachm (Silver, 2.33g, 12mm) ca 340-320 BC.
Obv: Bull walking to left atop dolphin; ΠΥ above
Rev: Quadripartite incuse square in the form of stippled 'mill sail' device.
Ref: SNG Stancomb 2, Schönert-Geiss 236-590; HGC 3.2, 1390