The Fasti of the Presbyterian Church in Ireland, 1840 - 1870, published by the Presbyterian Historical Society lists a Rev James Mitchell - details below:
James Mitchell, s[on] of John Mitchell, Clough, Down. Educ[ated] QCB [Queen's College Belfast] MCD, ACB, BA(QUI) 1866 [Queen's University of Ireland]; lic[enced] Down 5 May 1868; ord[ained] Curran [Co. Londonderry] 14 July 1869, res[igned] 17 March 1873; inst[alled] Calistoga Springs, Calif[ornia] 1873.
Hope this helps.