Watch List notes:

THRACE, Byzantion. Alliance coinage with Kalchedon. Late 3rd-2nd centuries BC. Æ (24.5mm, 10.16 g, 12h). Wreathed and veiled head of Demeter right / Poseidon seated right, holding aphlaston and trident; monogram to inner right. Schönert-Geiss, Byzantion 1257–75 var. (monogram); Türkoğlu A2a; HGC 3, 1428. Dark brown surfaces, brush marks, minor roughness. Good VF. Very rare with this monogram, missing from Schönert-Geiss.