Countermark

https://rpc.ashmus.ox.ac.uk/countermark/459 
GIC 339
eagle r. or l., head l. or r.
circular 
7–8 mm 
As 339i and 339ii. GIC suggested that the countermarks were applied no later than Gallus, but subsequent examples are on coins of Valerian, Gallienus and Salonina. 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC VII.2, 3110 Show 3110 9 7.2
RPC VII.2, 3021 Show 3021 8 7.2
RPC VII.2, 2997 Show 2997 5 7.2
RPC VI, 7078 (temporary) Show 6807 2 6
RPC VI, 7137 (temporary) Show 6828 5 6
RPC VI, 7137 (temporary) Show 6828 4 6
RPC VI, 7113 (temporary) Show 6850 3 6
RPC VI, 7091 (temporary) Show 6808 1 6
RPC VII.2, 3023 Show 3023 1 7.2
RPC VI, 7105 (temporary) Show 6845 6 6
RPC X, — (number not assigned), type ID 88146 Show 4128 1 10
RPC X, — (number not assigned), type ID 88264 Show 4119 1 10
RPC X, — (number not assigned), type ID 60599 Show 4132 5 10
RPC VI, 7091 (temporary) Show 6808 10 6
RPC X, — (number not assigned), type ID 60574 Show 4122 5 10