Septimius Severus Denarius. 

Obv: IMP CAE L SEP SEV-PERT AVG COS II, laureate head right 
Rev: S P Q R OPTIMO PBINCIPI (sic), Severus on horseback pacing left, spear in 
 right hand. 

RIC IV-1, 415, rated rare (Cohen 652) (The reverse misspelling of PRINCIPI is 
 also on other examples)

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