Mantinea, Arkadia, AE16 Dichalkon, ca 300-250 BC. 1.95 g. 

Helmeted head of Athena right.
MAN, Poseidon seated left on rock, holding dolphin and trident. 

BMC 19; BCD Pelop. 1487-1488; SNG Cop 252. 

With permission of Leu Numismatik, May 2006
BCD Sale, 1487.