Maximianus AE Antoninianus. 

IMP C M A VAL MAXIMIANVS P AVG, radiate, bare bust right, tie over shoulder 
CONSERVATOR AVGG, Emperor holding sceptre and Hercules leaning on club, face to face, sacrificing at altar. 

P in left field.
Mintmark XXI dot Lambda dot I

RIC V-2, 581, Siscia mint, rated rare (bust type)

Contributed by Dane for George Clegg (biggyg2), August, 2006.