Crispus AE3. 318 AD. Arles. 

CRISPVS NOB CAES, laureate draped and cuirassed bust right.
PRINCIPI IV-VENTVTIS, Mars standing left in military
dress, chlamys over left shoulder, resting left hand on 
shield on ground, and holding inverted, vertical spear in 
right.

Mintmark Q star-in-crescent A. 

RIC VII Arles 162, rated R4.

Courtesy of ancientcoinhouse, August 2010