Ptolemy IV, Egypt, 221-205 BC. AE 15mm, 3.47g.

Obv: Helmeted bust of a beardless male right
Rev: BASILEWS PTOLEMAIOU, Eagle standing left on 
thunderbolt, wings closed, filleted cornucopiae at shoulder

Svoronos 1155, SNGCop 235; Rare

An interesting mystery bust that I have not seen any real 
explanations for. The majority of the overse busts on AE
coins of Ptolemy IV are that of Zeus Ammon. Struck during 
the reign of Ptolemy IV, who ruled the Ptolemaic kingdom 
from  
This coin is pleasing in hand. The scanner made the edge look sort of green, almost like it has bronze disease. 

Courtesy of Romae Aeternae Numismatics, July 2010.
http://stores.ebay.com/Romae-Aeternae-Numismatics_Greek-Coins