Caracalla AE27 of Anchialus, Thrace. 

Obv: AV K M AVP ANTWNINOC, laureate, draped & cuirassed bust right 
Rev: OVLPIANWN AGCIAL-EWN, Serapis seated left holding a scepter and reaching 
 down to pet Cerberus at foot.

26x28 mm. 10.2 g.

Purchased by the Curator, July, 2003, from Roman Lode Ancient Coins,
http://www.vcoins.com/romanlode