Fiachra wrote:

> I think, although I haven't got a copy of Cath Magh Rath here right
> now, that he was chained by foot to the other fellow----they used to
> do that---chain the foot soldiers together so they wouldn't run away
> and it's part of the exaggeration in the telling that not alone did
> this chap swim all the way to Scotland but he did it with the other
> chap chained to his leg

I had thought that "ina chois" meant "by foot", but you are apparently right that it means "attached to his foot". Dillon, Cycle of the Kings, p. 64 says at the end of his
paraphrase of "Fled Dúin na nGéd":

"Of the Ulstermen only six hundred escaped; and of the foreigners one man alone, namley Dub Diad the druid, who flew through the air out of the battle and reached
Scotland with a dead warrior attached to his leg."

I  don't have a copy of FDnG, so I can't cite the original passage.