For background on how the map was made (and its flaws), see the relevant blog entry.
|Colgan||numerous: Dublin, Ulster, Midlands etc. Ir. Mac Colgan. From Colga, an early personal name. A sept in Derry was originally Ó Colgan; another was seated at Kilcolgan in Offaly. IF & SGG.|
|Mac Colgan||Colgan: cuíosach líonmhar: Ulaidh & Lár na Tíre. Bhí Mac Colgan suite ag Cill Colgan, Uíbh Flailí. Bhí Ó Colgan (ar dtús) ag Tír Ciabháin, Doire, ach tugadh Mac Colgan orthu sa 16 céad. Ón ainm pearsanta Colga.|
|MacColgan||fairly numerous: Derry-Tyrone etc. Ir. Mac Colgan, from old first name Colga. There were septs in Derry and Offaly. SGG.|