Linda, I have recently discovered a Cassidy / Hughes connection several generations prior to your request - my posting was in the Cassidy family page forum.
Another Cassidy descendant provided the following info to my Cassidy forum posting: Philip Cassidy, born 20 September 1814 in County Monaghan, Ireland, married Rose Hughes, born 26 August 1821, at Tyholland, County Monaghan on 17 June 1837. They had a son, James, in County Monaghan before emigrating to Providence, Rhode Island about 1840. In Providence they had five more children, Bernard (Barney), Peter, Mary, George and Margaret. They moved to Poy Sippi, Wisconsin 1850-51 where they had four more children, Ann, Philip Jr., Francis and Joseph.
I have no information on the Cassidy / Hughes family in Ireland other than this (but would love to discover more!).