I pulled this from the Encyclopedia of Legendary Creatures (Rand McNally 1981), which is a childrens book but I have found it to be an invaluable resource on the origin of many many differnt monsters and tales and it ussually gives me a name that I can follow up on in real research.
According to legend the people of the town of Nerluc, in France, once lived in terror of a winged, scaly dragon known as the tarasque. The creature had come swimming up the Rhone River from the east and made its home in a forest on the riverbank near the town. It preyed on unwary travelers making their way through the forest, and when there wasn't enough of them it would stalk into Nerluc and make a meal off the first person it encountered. Sixteen of the town's sturdiest and bravest men tried to kill the beast, but it killed eight of them and drove the rest to flight.
The Tarasque was finally conquered by a famous holy woman, Saint Martha. She sprinkled the beast with holy water, which made it harmless and tame, then led it into the town where the people beat it to death with clubs. The town took the name of Tarascon as a reminder that it once had the distinction of being preyed upon by the terrible tarasque.
Aaron.