Mac Oisticín
Mac OISTICÍN, Mac OISTIGÍN—V—M'Costikine, M'Costigine, M'Costegine, Costigan; 'son of Hodgkin' (diminutive of Hodge, i.e., Roger); often corruptly, in the spoken language, Mac Costagáin and Ó Costagáin, which see; a family of note in Ossory; apparently not of English descent, but a branch of some one of the great Irish families of that district.
Alphabetical Index to Irish Surnames