1. Bishop of Derkan or Airthir-muge, lived about A.D. 440, in the north of Ulster. He was found, when an infant, beside his dead mother, by Darius, a chief of Carsedna; and was baptized by St. Patrick, who later put him over the Church of Rath-mugia (or Airthir-mugia). St. Patrick afterwards sent him to Gaul, from which he returned (date uncertain), and was in all probability a bishop in A.D. 480. Ussher gives the date of his consecration as bishop of Derkan (or Clonderkan), in Dalriada, as 474. A story is told of his having been induced by menaces to baptize Saran, a chief in Dalriada; and of St. Patrick's foretelling that for his indiscretion his church would be thrice destroyed. Reeves notes that the Church of Armoy (Airthir-muge) has had its property gradually merged in the episcopal property of Connor, so that three fourths of the parish have been from time immemorial the property of that see. His day in the calendar is Feb. 20.
2. In speaking of St. Bolcan, Colgan (Acta Sancto rum, p. 377, n.) says there is another saint in Ireland called Bolcan, who is venerated in the church of Kill-chusle, County Roscommon; and that he is always enumerated by Tirechan and Aengus among the presbyters and abbots who were disciples of St. Patrick, being commemorated July 4. Alb. Butler (7, 61) says that his relics remain at Kilmore, where his monastery stood. Lanigan (Eccl. ist. Ir. i. 256, 344) calls him Olcan of Kilmoyle.