"Regia progenies alto de sanguine Machar". Now the learned editors of the Martyrology of Donegal inform us that the name _Mechar_ is the same as the _O'Meachair_ which appears so often in the ancient monuments of our history (see _Martyr. of Donegal_, published by I. A. S. 1864, pag. 517), and which at the present day has assumed the Anglicized forms of _Meagher_ and _Maher_. 4. The ancient Latin verses published in the _Record_,[3] present two important data for determining the family to which this bishop belonged. One is his native district, which is called _Solum Cariense_: the other is the royal ancestry to which his family had a just and ancient claim: "_Regia progenies alto de sanguine Machar_". Now are these data verified in the family of the O'Meachair? if not, it must be admitted that it can have no claim to our holy bishop; but if, on the other hand, those data accurately agree with what the ancient monuments of our island attest regarding the sept of the O'Meachairs, we must conclude that no link is wanting in the chain of evidence, and that the Blessed Thaddeus has justly been referred to that distinguished family. 5. Nothing now remains but to cite some few passages from our early writers which serve to illustrate these points in the history of the O'Meachairs. In the first place, the topographical poem of O'Huidhrin (who died in 1420) has one important passage which not only throws some light on the family name, but moreover points to the territory of _Ui-Cairin_ as the chief abode of the O'Mahers, precisely as the name _Carinum_ in the Latin poem cited above marks the native district of our holy Bishop Thaddeus. The translation of this poem of O'Huidhrin was the last work achieved by our illustrious O'Donovan, and was published by the I. A. S. in 1862. At page 133 we find the following verse:-- "Mightily have they filled the land The O'Meachairs--the territory of Ui-Cairin A tribe at the foot of Bearnan Eile; It is no shame to celebrate their triumph". To which lines O'Donovan adds the following notes: "_The O'Meachairs._ The name of this family is now Anglicized O'Meagher, but more generally Meagher or Maher, without the prefix O'. Their territory of Ui-Cairin is now called Ikerrin, and is a barony in the present county of Tipperary. "_Bearnan Eile_, i.e. the gapped mountain of Ely, now called in English the Devil's-Bit Mountain"--(Notes, page lxxxv., n. 71 and 72.) 6. In the _Leabhar na-Ceart_, edited by the same distinguished Irish antiquary, for the Celtic Society, in 1847, we find some additional evidence not only for the connexion of the _O'Meachars_ with the territory of _Ui-Cairin_, but also for the royal descent to which they laid claim. It is thus that _Leabhar-na-Ceart_ commemorates the tributes which were due to the king of Eile:--