Constantius II, AR Siliqua, 340-351 AD, Constantinople.

DN CONSTA-NTIVS AVG, pearl diademed, draped, cuirassed bust right.
FELICITAS REIPVBLICE around VOT XX MVLT XXX in four lines
within wreath.
Mintmark C dot A.

RIC VIII Constantinople 59 var (unlisted bust type)
At least R2.

With permission of Numismatica Ars Classica NAC AG, Auction 
54, lot 624.