Civil registrations are on the same website posted by hallmark. If your 2xgreat-grandparents had children in Ireland 1864 or later their births should have been registered, although not all were in the early years. Entry in register shows place of birth, father's residence and occupation, and mother's maiden name. Beware, some parents gave incorrect date of birth, so if you can't find a matching baptism, search baptism register(s) for a few weeks before official birth-date.