Johannes, AE4, Rome. AD 423-425. 

(DN IOHAN-NES PF AVG), pearl-diademed, draped and cuirassed bust right. 
VICTOR-IA AVGG, Victory walking left, holding wreath and palm, 
Epsilon in left field.
Mintmark probably RM (off flan). 

RIC X 1910 var (officina known but not for Johannes)

Although the Victory type with Epsilon in the left field 
and this reverse break was also struck e.g. for Theodosius
II (RIC X 1909), the style of the bust on this coin is more
likely to be Johannes.