Settṇtḭas or Settṇtḭos, while Seithennin or Seithenhin — both spellings occur in the Black Book — admits of being restored to Seithṇtinos, The nt in Setanta, on the other hand, makes one suspect that it is a name of Brythonic origin in Irish ; and I have been in the habit of associating it with that of the people of the Setantii, placed by Ptolemy on the coast-land of Lancashire. The two theories are possibly compatible ; but in that case one would have to consider both Setanta and Setantii as Brythonic names, handed down in forms more or less Goidelicised. Whether any legend has ever been current about a country submerged on the coast of Lancashire I cannot say, but I should be very glad to be informed of it if any such is known. I remember, however, reading somewhere as to the Plain of Muirthemhne, of which Cúchulainn, our Setanta, had special charge, that it was so called because it had once been covered by the sea : but that is just the converse of Seithennin's country being continuously submerged. The latter is beneath Cardigan Bay, while the other fringed the opposite side of the Irish Sea, consisting as it did of the level portion of county Louth. And on the whole I am not altogether indisposed to believe that we have in these names traces of an ancient legend of a wider scope than is represented by the Black Book triplets which I have essayed to translate. I think that I am right in recognising that legend in the Mabinogi of Branwen, daughter of Llyr. There we read that, when Bran and his men crossed from Wales to Ireland, the intervening sea consisted merely of two navigable rivers called Lli and Archan. The story-teller adds words, grievously mistranslated by Lady Charlotte Guest in her Mabinogion, iii, 117, to the effect that it is only since then that the sea has multiplied his realms between Ireland and the Isle of the Mighty, as he calls this country.
These are not all the questions which such stories suggest to me ; for Seithennin is represented in later Welsh
- There is another reading which would make them into Segantii, and render it irrelevant to mention them here.