Gaius Caesar Augustus (ruled 37–41) was called "Caligula" as a boy, for his "little boots" in which he accompanied his father Germanicus on campaign. As emperor he developed new coin types focusing on himself, his father, and his mother, Agrippina I, who was disgraced during the reign of his predecessor, Tiberius. The reverse of this coin focuses on his sisters, Agrippina II, Drusilla, and Julia, who are represented as Securitas, Concordia, and Fortuna, respectively. The obverse illustrates the connection between numismatic portraits, which bear the name of the emperor, and busts in the round, which invariably do not, both of which are on display in the Coins and Medals gallery.