From the similarity and almost complete identity of the meanings affixed to the words O and Mac in surnames, it might be expected that they should be popularly considered as conferring each the same respectability on the bearer; yet this is far from being the case, for it is popularly believed in every part of Ireland that the prefix O was a kind of title among the Irish, while Mac is a mark of no distinction whatever, and that any common Irishman may bear the prefix Mac, while he must have some claims to gentility of birth before he can presume to prefix O to his name. This is universally the feeling in the province of Connaught, where the gentry of Milesian descent are called O’Conor, O’Flahertie, O’Malley, &c.; and the peasantry, their collateral relatives, Connor, Flaherty, Malley. All this, however, is a popular error, for the prefix O is in no wise whatever more respectable than Mac, nor is either the one or the other an index to any respectability whatever, inasmuch as every single family of Firbolgic, Milesian, or Danish origin in Ireland, is entitled to bear either O or Mac as the first part of their surname. It is popularly known that O’Neill was King of Ulster, and O’Conor King of Connaught, and hence it is assumed that the prefix O is a title of great distinction; but it is never taken into consideration that O’Hallion was the name of the Irish Geocach or beggar who murdered O’Mulloy of Feara-Keall in the year 1110, or that _Mac_ Carthy was King of Desmond or Mac Murrough was King of Leinster! It is therefore a positive fact that the prefixes O and Mac are of equal import, both meaning male descendant, and that neither is an indication of any respectability whatever, except where the pedigree is proved and the history of the family known. To illustrate this by an example: The O prefixed to my own name is an index of my descent from Donovan, the son of Cathal, Chief of the Hy-Figeinte, who was killed by Brian Boru in the year 977; but the Mac prefixed in the surname Mac Carthy is an indication of higher descent, namely, from Carrthach, the great-grandson of Callaghan Cashel, King of Munster, whose descendants held the highest rank in Desmond till the civil wars of 1641. It would be now difficult to show how this popular error originated, as the meanings of the two prefixes O and Mac are so nearly alike. It may, however, have originated in a custom which prevailed among the _ancient_ Irish, namely, that, for some reason which we cannot now discover, the O was never prefixed in any surname derived from art, trade, or science, O’Gowan only excepted, the prefix Mac having been always used in such instances, for we never meet O’Saoir, O’Baird; and surnames thus formed, of course never ranked as high among the Irish as those which were formed from the names of chieftains.