(Μιθριδάτις), a daughter of Mithridates the Great, who had been at one time betrothed to Ptolemy, king of Egypt; but the marriage never took place, and she shared the fortunes of her father to the last. She and her sister Nyssa were present with Mithridates just before his death, and voluntarily took poison, that they might share his fate. (Appian, App. Mith. 111.)
[E.H.B]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890