Watch List notes:

GREEK COINS
THESSALY

Krannon. Late 5th or early 4th century BC. Hemiobol (Silver, 8mm, 0.44 g 7). ΠΙ Young male head wearing petasos to right. Rev. Κ-Ρ-Α Horse's head and neck to right, turned very slightly front. BCD 1437.1 (same dies). Extremely rare and of elegant style. Usual rough surfaces, otherwise, nearly extremely fine.

From a European collection, formed before 2005.
The great enigma about this coin concerns its obverse legend, Pi: what can it mean? Given the fact that the letters are the same size as those of the ethnic on the reverse they are surely not an artist's signature. The idea that they are an ethnic, thus making this tiny coin an alliance piece of some sort, founders on the fact that there are no cities or towns in the neighboring area that have a name beginning Pi.... Finally, the most likely is that the letters denote a magistrate, but one who financed this issue for the convenience of his fellow citizens, rather than just supervising its manufacture (thus the prominent size of the letters).