Bedd yr Afanc, 'the Afanc's Grave, [is] the name of some sort of a tumulus, I am told, on a knoll near the Pembrokeshire stream of the Nevern.Aw just give over, let it be a water monster, that's much more interesting. The grave is long and the monster is long.
Mr. J. Thomas, of Bancau Bryn Berian close by, has communicated to me certain echoes of a story how an afanc was caught in a pool near the bridge of Bryn Berian, and how it was taken up to be interred in what is now regarded as its grave.
A complete list of the afanc place-names in the Principality might possibly prove instructive. As to the word afanc, what seems to have happened is this: (1) from meaning simply a dwarf it came to be associated with water dwarfs; (2) the meaning being forgotten, the word was applied to any water monster; and (3) where afanc occurs in place-names the Hu story has been introduced to explain it, whether it fitted or not. This I should fancy to be the case with the Bryn Berian barrow, and it would be satisfactory to know whether it contains the remains of an ordinary dwarf.
Peredur's lake afanc may have been a dwarf; but whether that was so or not, it is remarkable that the weapon which the afanc handled was a ffechwaew or flake-spear, that is, a missile tipped with stone.
From Rhys's 1901 'Celtic Folklore Welsh and Manx', online at the Sacred Texts Archive
also see this page for more details (about the Peredur story, for instance):
Posted by Rhiannon
6th November 2006ce
Edited 14th March 2010ce