It may be here also remarked, that the O was never prefixed to names beginning with the word _Giolla_. I see no reason for this either, but I am positive that it is a fact, for throughout the Annals of the Four Masters only one O’Giolla, namely, O’Giolla Phadruig, occurs, and that only in one instance, and I have no doubt that this is a mere error of transcription. Another strange error prevails in the north of Ireland respecting O and Mac, viz. that every name in the north of Ireland of which Mac forms the first part, is of Scotch origin, while those to which the O is prefixed is of Irish origin; for example, that O’Neill and O’Kane are of Irish origin, but Mac Loughlin and Mac Closkey of Scotch origin. But it happens in these instances that Mac Loughlin is the senior branch of the family of O’Neill, and Mac Closkey a most distinguished offshoot from that of O’Kane. This error had its origin in the fact that the Scotch families very rarely prefixed the O (there being only three instances of their having used it at all on record), while the Irish used O tenfold more than the Mac. This appears from an index to the genealogical books of Lecan, and of Duald Mac Firbis, in the MS. library of the Royal Irish Academy, in which mention is made of only three Scotch surnames beginning with O, while there are upwards of two thousand distinct Irish surnames beginning with O, and only two hundred beginning with Mac. Another strange error is popular among the Irish, and those not of the lowest class, namely, that only five Irish families are entitled to have the O prefixed; but what names these five are is by no means agreed upon, some asserting that they are O’Neill, O’Donnell, O’Conor, O’Brien, and O’Flaherty; others that they are O’Neill, O’Donnell, O’Kane, O’Dowd, and O’Kelly; a third party insisting that they are O’Brien, O’Sullivan, O’Connell, O’Mahony, and O’Driscoll; while others make up the list in quite a different manner from all these, and this according to the part of Ireland in which they are located; and each party is positive that no family but the five of their own list has any title to the O. None of them would acknowledge that even the O’Melaghlins, the heads of the southern Hy Niall race, have any claims to this prefix, nor other very distinguished families, who invariably bore it down to a comparatively late period. On the other hand, it is universally admitted that any Irish family from Mac Carthy and Mac Murrough, down to Mac Gucken and Mac Phaudeen, has full title to the prefix Mac; and for no other reason than because it is believed to have been a mark of no distinction whatever among the ancient Irish. This error originated in the fact that five families of Irish blood were excepted by the English laws from being held as mere Irishmen. But of this hereafter.