Helena. AE4. 337-340 AD. Trier. 

FL IVL HE-LENAE AVG, draped bust right wearing ornamental mantle, 
necklace and broad hairband
PA-X PV-BLICA, Pax standing left holding branch and transverse
 sceptre. 

Mintmark TRS palmbranch. 

RIC VIII Trier 90 var, Sear 3910 var. 

None of the usual sources list the hairband for this Helena series, although I know of one from Constantinople. Rare.

With permission of Roma Numismatics, October, 2009