Gallienus, AE Antoninus, Rome. Sole reign.

Obv: GALLIENVS AVG, radiate head right
Rev: NEPTVNO CONS AVG, Hippocamp springing left. 
N in exergue.

Göbl 742b; VM.178/2

Note: Not in RIC with hippocamp springing left (RIC = 
springing right).
4 examples in Göbl.
Note the extra fins along the tail, as well as the odd 
placement of the end of the tail. No fins were shown on the 
backs of the forelegs. This hippocamp was also engraved very 
high up on the die, leaving a wide space below. Not just 
struck off-center, as you can also see parts of the beaded 
border.

Courtesy of Jim of www.lunalucifera.com/Zoo/