The earlier discussion Martin was thinking of was probably Lass of Acron?? (Lass of Aughrim). That mostly concerns the Joyce text, though in that case as it appeared in the film Nora.

It may be that the song is that film was sung to a different tune from the one used in The Dead; Murray on Saltspring identified the former as the 'Lass of Lochryan' tune from the (Scottish) Blaikie MS. Whether or not anybody really knows what tune Joyce knew for it is hard to tell.