I was an underbidder in this rare coin which just sold for $321. It is a rare example (r5 in RIC) of a SOL with one captive in the exergue.
Wow! I've never seen any exergue like that. I wonder if it signified anything specifically?
I would guess that it references the troubles with the Germanic tribes in the Gaul region. Crispus was victorious in military operations against the Franks and Alamanni in A.D. 318 and 320 and this SOL coin was issued in A.D. 318.
here's another example with captive facing right, RIC 184; Ferrandon 228. 20mm 2.8gm