'Seed of Muiredach'; Anglicized Sil Murray or Silmurray), was a leading sept of the Connachta group of Gaelic dynasties in medieval Ireland.
The major division within the tribe was between the descendants of Muireadhach's two sons, Indrechtach and Cathal (a quo Clann Cathail), who would both go on to become Kings of Connacht.
The family groupings within Clann Cathail shown below are as listed in McFirbis' Leabhar na nGenealach (The Great Book of Irish Genealogies).
In addition to the family groupings below McFirbis lists 13 other surnames that he says also belonged to Clann Cathail: O'Mothlachain, O'Dathail, OhUllsa, O'Cloithfhilidh, O'Gusain, O'Fionnagain, O'Laighin, O'Laoghog, O'Tomhrair, O'Caomhoige, O'Breslein, O'Dubhain, and O'Fannain.
The O'Flanagans had their main seat in Mantua (previously called Mointeach) which is located along the southern borders of Cloonyeffer and Corry East townlands in Shankill Parish.