I found mention of similar names to what you posted in another publication titled IRELAND IN THE MIDDLE AGES, C. 1300. There wasn't a "Rushfin" but there was RUSH, County Dublin Map name: Ros Eo Modern Irish Name: An Ros Type: Manor or village Meaning: 'the headland' When looking for "Innishfin" I found INISHBOFIN, County Galway Map name: Inis bo Finne Source: Joyce First Record: Inis bo Finde Source: Bede Modern Irish Name: Inis Bo Finne Type: Celtic religious foundation Meaning: "inis 'island' of the 'white cow'" - in legend there was a white cow which appeared at certain times over the waters of a lake on the island. Just hazarding a guess, maybe the "bo" stands for "cow". If you left out the "bo", maybe Inishfin means 'white island'? That's an uneducated deduction!!!!!