Watch List notes:

Anonymous. 157-156 B.C. AE triens (21.68 mm, 5.40 g, 1 h). Rome mint. Helmeted head of Minerva right; four pellets above / ROMA, prow of galley right; four pellets below. Crawford 198b/3; Sydenham 302b. VF. Overstruck on a Semis. Very Rare. 

Ex RBW collection (not in previous sales). 

Very rare, only two specimens in Paris. Overstruck on a Semis