Septimius Severus, AE17, Nikopolis ad Istrum.

AV K CEVHROC, laureate head right.
NIKOPOLIT PROC ICT, fourfold coiled serpent with head 
lowered, left.

Varbanov 2392 (this coin); Moushmov 949.

Ancient Coin Art 2003. Found in an orphaned folder and
added June 2011.

Note: Varbanov lists 16 coiled serpent types, with
different obverse and reverse legends and bust types: one
with serpent's head up, right; three with four coils and
head lowered left; five with four coils and head lowered
right, six with two coils and head lowered right and one
with radiate head lowered right.