Caligula AE20 of Byzantium, Thrace.

GAIOY KAISAROS GERMANIKOY, bare head left, two countermarks:
male head right and dolphin.
BYZANTION, prow left.

Varbanov 1622; Schönert-Geiss 1312-1313; RPC 1781

With permission of cngcoins.com, Feb. 2009.