Nellie d 1899 so 1880 would be the only census she would be listed. It's also possible Mary Ellen's birth record was adjusted to show adoptive parents
Be ever so careful....there are many Murtys in Galway.I believe the Murty b 1809 incarcerated 1839 Galway, probably not yours. Possibly the same person [b 1809] 1880 Lewis Co WV with his bro Daniel.I would think your Murty would've been born much later.
But, are you positive Murty's dau Nellie is the mother of Mary Ellen?