That the name Llydaw did on occasion refer to the region of Llyn Syfadon admits of indirect proof as follows:--The church of Llangorse on its banks is dedicated to a Saint Paulinus, after whom also is called Capel Peulin, in the upper course of the Towy, adjacent to the Cardiganshire parish of Llandewi Brefi. Moreover, tradition makes Paulinus attend a synod in 519 at Llandewi Brefi, where St. David distinguished himself by his preaching against Pelagianism. Paulinus was then an old man, and St. David had been one of his pupils at the Ty Gwyn, 'Whitland,' on the Taf, where Paulinus had established a religious house [128]; and some five miles up a tributary brook of the Taf is the church of Llandysilio, where an ancient inscription mentions a Paulinus. These two places, Whitland and Llandysilio, were probably in the cymwd of Peuliniog, which is called after a Paulinus, and through which we have just followed the hunt of Twrch Trwyth (p. 512). Now the inscription to which I have referred reads [129], with ligatures:--
This probably means '(the Monument) of Clutorix, son of Paulinus from Latium in the Marsh'; unless one ought rather to treat Marini as an epithet to Paulini. In either case Latio has probably to be construed 'of or from Latium': compare a Roman inscription found at Bath (Hübner's No. 48), which begins with C. Murrius. | C. F. Arniensis | Foro. Iuli. Modestus [130], and makes in English, according to Mr. Haverfield, 'Gaius Murrius Modestus, son of Gaius, of the tribe Arniensis, of the town Forum Iulii.' The easiest way to explain the last line as a whole is probably to treat it as a compound with the qualifying word deriving its meaning, not from mare, 'the sea,' but from the Late Latin mara, 'a marsh or bog.' Thus Marini-Latium would mean 'Marshy Latium,' to distinguish it from Latium in Italy, and from Letha or Llydaw in the sense of Brittany, which was analogously termed in Medieval Irish Armuirc Letha [131], that is the Armorica of Letha. This is borne out by the name of the church of Paulinus, which is in Welsh Llan y Gors, anglicized Llangorse, 'the Church of the Marsh or Bog,' and that is exactly the meaning of the name given it in the Taxatio of Pope Nicholas, which is that of Ecclesia de Mara. In other terms, we have in the qualified Latium of the inscription the Latium or Letha which came to be called in Welsh Llydaw. It is, in my opinion, from that settlement as their head quarters, that the Men of Llydaw sallied forth to take part in the hunt in Ystrad Yw, where the boar Llwydog was killed.