Istros, Thrace, AR Trihemiobol, 11 mm, 1.30 g. 4th century BC. 

Facing male heads, the right inverted.
ISTR, sea-eagle left on dolphin, PA monogram beneath dolphin. 

AMNG 444; Canarache 368.

With permission of Pecunem Gitbud & Naumann - Auction 33, Lot 45, July 2015.