Watch List notes:

THESSALY. Perrhaiboi. Circa 450-430 BC. Trihemiobol (Silver, 15 mm, 1.34 g, 6 h). Thessalian cavalryman, wearing petasos and chlamys and holding two spears, riding horse walking to left; below horse, altar; border of dots. Rev. Π-Ε-Ρ-Α (retrograde) Athena (?), draped, seated to left on high-backed chair, holding a crested, Corinthian helmet in both hands and resting her feet on a low foot rest. BCD Thessaly II, 547 (this coin). SNG Copenhagen 194. Lightly toned, clear and struck on a broad flan. Good very fine.
From the "Collection sans Pareille" of Ancient Greek Fractions, and from the BCD Collection, Triton XV, 3 January 2012, 457.