This coin is a bit worn, but it has a decorated shield…emperor on horseback. Bastien notes two different shield decorations for this number (#210a)…empereur à cheval, like this one, and an example with a trophy and prisoner on either side (#210b).
Constantius I
26mm 8.6gm
A.D. 301- 303
CONSTANTIVS NOB CAES; facing left, laureate, cuirassed, spear over right shoulder, decorated shield on left; B in right field.
GENIO POPVLI ROMANI; Genius standing left, modius on head, naked but for chlamys over left shoulder, right holding patera, left cornucopiae.
In ex. PLC
RIC VI Lyons 150