This seems to be an unlisted intermediate issue between 321 AD
(dot AQT dot) with ..IVN NOB CAES and 322 AD (AQT with 2 palm
branches).
This is definitely an ..IVN NOB C with dot AQT dot, and the
closest coin to it would be RIC VII Aquileia 101, so I'll call
this 101 var.

Obv: Constantine II, CONSTANTINVS IVN NOB C, laureate, 
     draped, cuirassed bust right (bust type B4)
Rev: CAESARVM NOSTRORVM around laurel wreath containing
     VOT /(dot)/ X (whereby the dot in the
     centre is often considered to be a centering mark)
In Ex: dot AQT dot
Ref: RIC VII Aquileia 101 var.
Unlisted for this obverse legend, possibly intermediate issue 
between 321 and 322 AD

Contributed by Dane, May, 2004.