It may be that there is no "th" sound in the Irish language, so a native Irish speaker would never need to use the sound. Later when using English, the use would continue. Mind you the Celtic languages were in use long before English was ever even thought of.To Martin Ryan - me too and proud of it. To Alice - "croothen" is just the sound of "cruite" and "na mbo" pushed togther making it sound as "croothen amow."