VRBS ROMA, Rome City Commemorative
AD 330-346
AE4. 1.39g, 16.5mm
MINTED: Heraclea mint, AD 330-335
REF: RIC VIII Heraclea 156 (R2)
OBVERSE: VRBS-ROMA, helmeted bust of Roma with visor and crest wearing imperial mantle left.
REVERSE: GLOR-IA EXERC-ITVS, two soldiers standing facing, head turned inward at one standard betweeen them, o on banner, each soldier holding a spear; SMHЄ in exergue.
 
Notes:
Brown patina; rough surfaces. 
A scarce issue, pairing the VRBS ROMA obverse with a GLORIA EXERCITVS reverse rather than the common she-wolf and twins type. 
According to Victor Clark, these are not 'mules' or 'hybrids' but, “coins intentionally designed with "retro" reverses. They were issued by the sons of Constantine after the old man had passed away, and all appear in a reduced module closer to the range of an AE4 than the earlier coins.”
 
Historical Notes:
The VRBS ROMA coins were part of a commemorative series issued by Constantine the Great and his sons between AD 330 to 346.  Along with the other types (such as the CONSTANTINOPOLIS coins), they served to celebrate the founding of Constantinople as Constantine's new capital city, while at the same time acknowledging Rome as the Empire's original birthplace.  The 'wolf and twins' motif was a traditional one depicting the twins Romulus and Remus being suckled by a she-wolf who sheltered them after they had been left abandoned in the wilds.  Romulus was the mythological founder of the city of Rome.