Watch List notes:

Thrace, Byzantion in alliance with Kalchedon Æ 23mm. 3rd century BC. Veiled head of Demeter to right / Poseidon seated to right, holding aphlaston and trident; ΒΥΞΑNT to right, ΚΑΛΧΑΔ to left; monogram below feet. Cf. HGC 3.2, 1428. 11.54g, 23mm, 12h.

Good Very Fine. Very rare with monogram below feet.

From the inventory of a UK dealer.