Egans of County Mayo 1840

I ve just begun my research into my Egan side of the family as I will be coming to Ireland this summer.  Thomas Egan (Roman Catholic) born 1807 Co. Mayo -1863 Westport Ontario Canada married Ellen Bridget Mulvihill (Roman Catholic) of Ireland, County ??? born 1819 died in 1896 Westport, Ontario Canada. From what I have researched Ellen's parents were James Mulvihill and Catherine Scanlan. I do not know Thomas' parent's names.  Thomas and Ellen's first child Margaret in one Canadian document is recorded as being born in Ireland (1840) in another document it is recorded that she was born in Canada.  If she was born in Ireland in 1840 and the second child Mary who was definitely born in Canada in 1841 I've concluded that the Egans came over in 1840-41. All their other children Michael, Patrick, Thomas and John are shown in the 1851 census to have been born in Canada. Mary Egan marries my gggrandfather Michael Killeen who was born 1841 in county Clare and came to Canada in 1849.  Another generation of Egans actually marries into the next generation of the Killeen family. Looking to learn more of where my Egans of county Mayo are actually from so I might include a visit to the area in my itinerary this August.