Rhizostama jellyfish?

Hi,
I was stung by a jellyfish in a lagoon off Luecate, Southern France on 13 August 2012. I have googled images and types and believe it to be a Rhizostome jellyfish. Its size appeared to be quite impressive,its head probably 15 - 25 cms in diameter with a deep violet 4-5mm fringe/belt around it. I didn't get to see the tentacles, as my husband, son and I virtually jumped out of the water. There were many more jellyfish slightly away from the shore (but not too deep, standing height) approximately 7-11 per square meter.