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Ptolemy III, AE28 trihemiobol, 246-222 BC. Alexandria mint. 16 g. 

Laureate head of Zeus right. 
PTOLEMAIOU BASILEWS, Eagle standing left on thunderbolt, wings spread. 

C (degraded E or Epsilon) between legs, filleted cornucopiae in left field.

Svoronos 975 type 3 (E resp. epsilon). 

The C is known on several examples but is not in Svoronos.