Watch List notes:

The Roman Empire
Gaius, 37 – 41

Denarius 40, AR 3.72 g. C CAESAR AVG PON M TR POT III COS III P P Laureate head of Gaius r. Rev. AGRIPPINA MAT C CAES AVG GERM Draped bust of Agrippina r. C 6. BMC 23. RIC 22. CBN 32 (Lugdunum). Banti 26 (this coin).
Very rare. Two bold portraits of fine style and a lovely old cabinet tone.
Minor marks, otherwise extremely fine / about extremely fine

Ex Hess 211, 1932, Webb, 331 Glending 1969, 36; Sternberg 1, 1973, 54; Leu 50, 1990, 276 and NAC 46, 2008, 503 sales.
Agrippina senior, mother of Caligula, is depicted on this coin with a beautifully executed portrait. This issue has two basic types, one with a larger head and one with a smaller but higher quality portrait head like the one offered here. AMP.