Constantine II with horse in the observe

[Corduba]

Yesterday, I bought this coin. I think is really a rare coin.
I´m try to catalog it but I can´t find it.
Can you help me?
OBSERVE:
CONSTANTINVS IVN. N.C.
Laureate, draped, cuirassed half length body, spear over shoulder, shield on arm, holding horse by bridle with right hand.

REVERSE:
BEATA TRAN-QVILLITAS.
Altar with VOT/IS/XX
Exergue. I think is P-TR.

Weight: 2,13 gr.
Size: 17 mm.

Thanks, Ignacio.

[Victor]

I can't make out your mintmark so I am not sure of the RIC number or if it is unlisted. The best reference for these coins is Alten & Zschucke's Die romische Munzserie Beata Tranquillitas

Below is an example that I have that is very similar to yours though.


Constantine II
A.D. 323
CONSTANTINVS IVN N C; laureate and cuirassed bust left, decorated shield on left arm, spear over shoulder, holding horse by bridle with right hand.
BEATA TRAN- QVILLITAS globe set on altar inscribed VO/TIS/XX; above, three stars.
in ex. •PTR crescent
RIC VII Trier 415

 
Shield decorated with two people, maybe Constantine I and Constantine II, shaking hands.

[Corduba]

Victor,
Thanks for the reply.

I´d try to take a better picture but I´m really bad.
Anyway the exergue is PTR crescent (almost sure).

I´m really happy to find this coin from a local dealer in my town.
It´s the first time I have this observe.

Best regards, Ignacio.