Bithynia, Kalchedon AR Siglos or Drachm (Silver, 3.64g, 13mm) Persic standard, ca 340-320 BC.
Obv: Bull standing to left on grain ear; KAΛX above
Rev: Incuse granulated mill-sail pattern.
Ref: SNG Black Sea 112-117; SNG von Aulock 482; HGC 7, 517