Carausius, AR denarius, semi-barbarous. 

Obv: INP CARAVSIVS (INV?) (M engraved as retrograde N), 
radiate, draped bust right.
Rev: ADVENTVS AVG (N retrograde), Carausius riding left, 
holding sceptre and branch, captive beneath horse's
front hooves. 
No mintmark. 
RIC 706 var (legends and reverse attributes); Sear 13496 var (ditto).

Courtesy of TimeLine Auctions (www.timelineauctions.com), February, 2013, item 13932.