There's a James Marcus and a James McAlonan both living in the townland of Loughconnelly, parish of Skerry, in the 1861 Griffith's Valuation. Familysearch.org has a marriage between a Thomas Marquis and a Jane McElhone. There is no marriage date but the birth years correspond. Perhaps McElhone became McAlonan. There is also the birth of a son Samuel Marcus in 1833 in 'Conyer' to a Thomas Marquis and Jane McElhone. Regards Nevin