Constantine I VOT XX consular bust from Rome

[Victor]

someone sent me a picture of this fairly rare type for Constantine I, unfortunately it is in rough condition. He is laureate, wearing a trabea and holding an eagle tipped sceptre. The only one like this in RIC is from Rome (RIC VII Rome 227), though  I have heard of an example from Arles. However, the mintmark is not clear on this coin.