This notable Irish surname is an Anglicized form of the Old Gaelic "O'Ciardhubhain", descendant of Ciardhubhain, a male given name composed of the elements "ciar", dark, swarthy, "dubh", black, and the diminutive suffix "-an". Traditionally, Irish family names are taken from the heads of tribes, revered elders, or some illustrious warrior, and are usually prefixed by "Mac", denoting "son of", or "O", grandson, male descendant of. The great "O'Ciardhubhain" sept go back to Heremon of the Milesians who probably came from Spain, and they are first recorded in history as erenaghs of County Louth. The duty of erenagh families was to hold church property from generation to generation, and generally to maintain a priest. Early Anglicized forms of the name include: Kerovan, Kyrvan and O'Quirivan, whence the County Clare placename Craggykerrivane. Following their move to Galway in the 15th Century the Kirwins, with the Darcys, were the only families of Gaelic origin to be accepted into the Fourteen Tribes of Galway, becoming second only to the Lynches as a leading family of that city. They produced several distinguished ecclesiastics, and an Irish family of Kirwan established in Dauphiny was ranked among the nobility of France. On March 14th 1866, the birth of Patrick Kirwin was registered at Roundstone, County Galway. The family Coat of Arms is a silver shield with a black chevron between three Cornish choughs proper. The first recorded spelling of the family name is shown to be that of O'Ciardhubhain, an erenagh family, which was dated circa 1400, in "Ecclesiastical Records of County Louth", during the reign of King Henry 1V of England, known as "Henry of Bolingbroke", 1399 - 1413. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.