Julia Domna AE23 Trias of Tomis, Thrace. 

IOVLIA DOMNA CEB, draped bust right.
MHTPO PON TOMEOC, Posiedon standing right, holding 
trident and dolphin, value mark Gamma to right.

Varbanov 4873 (this coin); Moushmov 1915

From a pre-1994 German auction.