in Ancient Geography, a small river of Etruria, falling into the Tiber not far from Rome. On the banks of this river the 300 Fabii established themselves when they set out from Rome on their expedition against the Vejentes, and kept the enemy in constant alarm, till they were surprised in one of their sallies, and cut off to a man, &c. 477. This disaster occurred on the 16th of July, on which day many years later the Romans sustained the terrible defeat of the Allia. Some modern geographers have identified the Cremera with the Fosso di Valca; others, on apparently better grounds, with the Aqua Traversa, which falls into the Tiber about three miles from Rome.