Sel is right. It's a lot of fun to see how close you can come to fully attributing a coin. In this case, I think I have it narrowed down to one of two fairly close samples. The first, and the one I think best matches, is
1. Commodus. AE Sestertius, RIC 3, 550. 189 AD. Rome. M COMMODVS ANT P FELIX AVG BRIT, laureate head right / ROMAE AETERNAE, Roma seated left, shield at side, holding Victory and upright spear. S-C across fields, COS V PP in exergue.
http://wildwinds.com/coins/ric/comm...RIC_0550.jpgAnd the second possibility might be:
2. Commodus AE Sestertius, RIC3, 583. 190-191 AD. M COMMOD ANT P FELIX AVG BRIT PP, laureate head right / ROM AETER PM TRP XVI COS VI P P S-C, Roma seated left holding Victory & spear, shield by seat.
http://wildwinds.com/coins/ric/comm...IC_0583v.jpg