Countermark

https://rpc.ashmus.ox.ac.uk/countermark/180 
GIC 58
male head r. (emperor?) (on reverse)
oval or circular 
6 x 4 mm 
Sometimes on reverse 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 1111 Show 1111 2 1
RPC I, 1113 Show 1113 14 1