Watch List notes:

BOEOTIA. Mykalessos. Circa 400-375 BC. Obol (Silver, 10.5 mm, 0.87 g). Boeotian shield. Rev. M - Y Thunderbolt; all within an oval incuse. BCD Boeotia 178. BMC 1. HGC 4, 1231. SNG Copenhagen 190-191. With a pleasant grey patina. Good very fine.
From the "Collection sans Pareille" of Ancient Greek Fractions, ex Münzen und Medaillen FPL 259, November 1965, 28, and from the collection of T. Prowe, Egger XL, 2 May 1912, 897.