... In the Mabinogion, or Romantic Tales, one of the achievements of Paredur is the slaying of the addanc y llyn, or crocodile of the lake, at the Hill of Lamentation.  And a poet of the fifteenth century, in soliciting a suit of armour from his patron, compares the workmanship to the "wonderful scales on the fore legs" of the avanc.
    According to the Welsh Laws this animal was at one time common in Wales; and Giraldus Cambrensis speaks of it as being found in his time in the river Teifi.  It has also been called addanc and llostlydan, which latter seems to mean the beaver, an animal that is said to have been seen in Nant Ffrancon, in Caernarvonshire, at no very remote period. (Cambro-Briton, v.1, 1819)