Countermark

https://rpc.ashmus.ox.ac.uk/countermark/613 
GIC 488
?, 'thyrus'
Sometimes on reverse 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 1420 Show 1420 4 1
RPC I, 1420 Show 1420 6 1
RPC I, 1420 Show 1420 7 1
RPC I, 1420 Show 1420 13 1
RPC I, 1420 Show 1420 14 1