Thanks! ...just wondering ...some of these things are "educated guesses" ...anyway even by the experts.
My own last name, Foley, arose in two different areas of Ireland from unrelated derivatives. I had assumed mine was the more popular in the south since most of my family is from there. It comes from 'fohglai', meaning a robber or plunderer while the other is in the west from a mistranslation of the word 'serraich' which is a small horse ...or a foal. It wasn't until I learned that the birthplace of my great grandfather was in Roscommon that I finally concluded mine must be descended from 'serraich' ...in all probability.