... The Nennian Genealogies distinguish the two.  Cunedda's father is there called Aetern, his grandfather Patern (that is Paternus), and his father Tacit (that is Tacitus); while a son of Cunedda is called Etern—the family was par excellence a Christian one, and many Biblical names were used by others of its members.  The names of the other class in these genealogies are Ritigern, Cattegirn, and Outigirn [Outigir], which become later respectively Rhydeyrn, Catteyrn, and Eudeyrn—the last would seem to have survived as Edeyrn.  On the other hand, false etymology has led to Etern, which is now Edern, being sometimes written Edeyrn; but it has not been able to touch the pronunciation, all the former set being accented Rhydéyrn, Cattéyrn, Cyndéyrn, and so on; while the latter is Edern as in the places called after the saint of that name, such as Llanédern, in Lleyn, and Bodedern, near Holyhead... (The Academy and Literature, v.21, 1882)