Recorded in various and diverse forms such as MacBrearty, McBrearty, McCurdy, McMurtyr, McMurthy, McMerty, MacMearty, O'Murtagh and Murtagh, this is an Irish surname. It is or rather was originally, generally specific only to the province of Ulster and the county of Donegal, where it is claimed to be a form of the Scottish MacMurdoch. The famous etymologist, the late Edward MacLysaght appeared to believe that it derived from the pre15th century Mac Muirchertaigh, meaning the son of the navigator, which would make it the same origin as the surname O'Murtagh, or the gransdon of the navigator. If in fact the surname did originate from some (by medieval standards), far away place like Scotland, to be called the navigator, would seem to be a logical explanation for the meaning. As to why so many apparently associated spellings forms have developed, is one of the mysteries of surnames in Northern Ireland, where probably nowhere else on earth are there so many different names within such a relatively small population. It is said that the name was first recorded in Petty's Census of Ireland in 1659 with members of the clan holdings lands in that county, but because of the paucity of records it is not until the Great Famine of 1846 - 1848 that we are able to quote definitive records. These are from the Port of New York arrivals lists and include Catherine Murtagh aged twenty on the ship "Sheridan of Belfast", on June 20th 1846, Alexander McCurdy, aged eighteen and given as being a coachman, on the ship "Niagara of Liverpool", on June 9th 1846, and Catherine McBrearty, on the "Marion of Londonderry", on April 12th 1847.