This Saturninus was a 3rd-Century missionary from Rome to Gaul, the Pyrenees, and the Iberian peninsula who, with a farmer now known as St Honestus, whom he had converted, was imprisoned at Carcassone by the prefect Rufinus, but they were freed by an angel. As the first bishop of Toulouse, France, he teamed with St Martial to perform miraculous healings. When Saturninus began his work in Toulouse, the local pagan priests stopped receiving oracular messages from their gods. One day in 257, pagan idols fell to pieces in front of the bishop, so the crowd murdered him, his punishment being dragged to death by a bull. Or so it is said.
More at November 29, in Wilson's Almanac online.