Anonymous AE16, Festival of Isis. Mid 4th century AD. Rome mint. 

[DEO S]E-RAPIDI, radiate and draped bust of Serapis right, modius on head.
VOT[A] PVB[LIC]A, Isis standing left, holding sistrum 
and reins, in tensa or biga drawn left by two mules. 

Cf. RIC VIII 500-1 (for rev. type; Julian II); Alföldi, 
Festival 207; Vagi 3371. 

With permission of cngcoins.com, Electronic Auction 229, March 2010.