Pretty extensive site there. I looked under the Celtic Traditions and the Fairy Tales in the European section and didn't find this one, which I link to from my page on the Gartan Mother's Lullaby. http://www.alia.ie/tirnanog/sochis/vb.html click here As part of the history of ancient Ireland, it defines the gods, goblins, and phantoms, such as in the lullaby, Aebinn or Aibell [Eevin, Eevil] of Craglea, the grey rock. "Aibell from the grey rock comes, to wrap the world in thrall..."
and "Sheevra [siabra] sails his boat til morn, upon the starry bog"

Alice