CRISPUS, as Caesar. 317-326 AD. AE nummus (2.66 gm). Trier, 322-323 AD. 

Obv: IVL CRISPVS NOB CAES, bust laureate, draped, cuirassed 
right, half-length, holding spear in right hand and horse by
the bridle in left hand.
Rev: BEATA TRANQVILLITAS, globe on altar inscribed 
VO/TIS/XX, three stars above
Mintmark dot PTR dot. 

RIC VII Trier 372 var (obverse type)
also cf. RIC VII 381 for Constantine II.

Photo courtesy HJB Coins.
Note: The original images were lost in the destructive
attack of wildwinds in Spring 2009. Fortunately I
found the original image online. DK.
Re-added, Sept 2010.