Carausius AE Antoninianus. C mint. 

IMP CARAVSIVS PF AVG, Radiate, helmeted, cuirassed bust 
left, holding spear and shield
SALVS AVG, Salus standing left by altar, holding sceptre, 
feeding serpent rising from altar.
Mintmark C.

RIC V-2, Camulodunum 398 var (bust type)
Rare.