Watch List notes:

AKARNANIA. Stratos. Circa 425-400 BC. Diobol (Silver, 10.5 mm, 0.90 g, 12 h). Bearded facing head of the androkephalic, horned, river-god Acheloos, turned very slightly to the left. Rev. [Σ-Τ]-R-Α (partially retrograde) Head of the nymph Kallirhoe to left, her hair bound up at the back; all within an incuse square. HGC 4, 932 (same dies). Traité II, 4, 3 and pl. CCLXXI, 3 (same dies). Very rare. Nicely toned and with a remarkably expressive and emotional head of Acheloos. Reverse struck from a worn die, otherwise, good very fine/fine.
From the "Collection sans Pareille" of Ancient Greek Fractions, and from the collection of L. Mildenberg, ex Münzen und Medaillen FPL 115, July 1952, 12.