COROTICUS: This name was formerly identified with Ceredig, the name of the Welsh prince who gave name to the county of Cardigan in South Wales. Sir Samuel Ferguson (Patrician documents, xxxii) first pointed out that the individual meant was Ceretic Guletic ('prince'), the ruler of Alcluith or Strathclyde, c. 420—450 A.D., and Prof. Zimmer (Celtic Church, p. 54—55) has proved this conclusively Muirchu, the biographer of S. Patrick, calls him "Coirthech regem Aloo," king of the rock (Alclwyd). In two passages of S. Patrick's letter to the subjects of Coroticus (c. 2, 15) he applies the epithet 'apostate' (Pictorum apostatarum) to the Picts that were allies of Coroticus. "It is not clear," says Rev. Dr. White, "why they were called 'apostate;' perhaps on account of their having joined Scottic heathen in a raid on Patrick's Scottic Christians; perhaps because of an actual lapse into formal heathenism. In any case," he adds, "it proves that they had once been Christians" (St. Patrick, p. 5). The mission of S. Ninian of Wbitherne to the Southern Picts is dated between 394 and 432.