Section 49. Every office and position the salary of which is wholly payable from the treasury of one or more counties, or from funds administered by and through county officials, excluding the offices of county commissioners, the register of deeds and the assistant registers of deeds for the county of Suffolk, the sheriff of the county of Suffolk, and excluding offices and positions filled by appointment of the governor with the advice and consent of the council, and offices and positions payable under chapter twenty-nine A, shall be classified by the board in the manner provided by sections forty-eight to fifty-six, inclusive, and every such office and position, now existing or hereafter established, shall be allocated by the board to its proper place in such classification. Offices and positions in the service of any department, board, school or hospital principally supported by the funds of the county or counties, or in the service of a hospital district established under sections seventy-eight to ninety-one, inclusive, of chapter one hundred and eleven, shall likewise be subject to classification as aforesaid. The word ''salary'', as used in this section, shall include compensation, however payable; but nothing in sections forty-eight to fifty-six, inclusive, and nothing done under authority thereof, shall prevent any person from continuing to receive from a county such compensation as is fixed under authority of other provisions of law or as is expressly established by law.