"Severeia of the Nicaeans" In the late 3rd century a complex cycle of at least fifteen games and associated religious festivals is attested for Nicaea, honoring Dionysus the founder, Apollo Pythius, and various emperors from Augustus to Gallienus. Read along with the very young portrait of Caracalla as Augustus, the legend and type can be taken to indicate that Nicaea sponsored a grand series of festivals to celebrate the joint elevation of Caracalla to Augustus and Geta to Caesar in 198 AD.
For the discussion of the reverse type see:
http://www.forumancientcoins.com/board/index.php?topic=28925.msg188295#msg188295
http://homepage.univie.ac.at/elisabeth.trinkl/forum/forum0300/14specht.htm