Constantius II AE2. 351-355 AD. 

D N CONSTANTIVS P F AVG, pearl diademed, draped, cuirassed bust right
FEL TEMP RE-PARATIO, soldier standing left, right knee
 raised, spearing fallen horseman, who is wearing Phrygian
 helmet, no beard, clutching horse's neck, Gamma in left 
field, dot in centre, 
Mintmark CONSI. 

RIC VIII Constantinople 106.

See my RIC list of all Fel Temp Reparatio types,
in Excel format, with drop-down column entries to
find a reference within seconds:
www.catbikes.ch/coinstuff/coins-ric.htm

Submitted by Dane for Constante, Sept 2012.