Garsten households in mid-nineteenth century Ireland
No Garsten households in Griffith's.
Surname Dictionary
MacCarrison
rare: Down etc. Mac Corsain: Scottish from Galloway. See also Carson. SS.
MacCorriston
Quite numerous: Derry-Donegal etc. Ir. Mac Orraistín (SGA). Black mentions a place in Dumfries called Macorriston which he thought might derive from Corish, q.v.