Successive conquests and cultural changes have taken a heavy toll of Irish libraries, but enough remains to show just how rich the apocryphal collections would have been. Modern scholars like Martin McNamara, Máire Herbert and David Dumville have painstakingly collected these records, discussing over a hundred items known in Ireland. Many are poetic elaborations of well-known stories, but we also find a full spectrum of widely known alternative texts. In many cases, the texts survive in the vernacular, in Irish Gaelic.
See also Jenkins' earlier post on "Canons of Scripture," which reflects the nuances of current discussion about the canon of the New Testament and the interplay of canonical and non-canonical texts over the centuries.