17. All lands held without payment of rent, not being entered on the Collector's register of revenue-free tenures of the district, shall, for the purposes of this Act, be deemed to form a part of the tenure within the local boundaries of which they may be included; and if they be not included within the local boundary of any tenure, then to be a part of the estate within the local boundaries of which they are included, and if they be not included within the local boundaries of any one estate, then to be a part of such conterminous estate as the Collector in whose district such conterminous estate is situated shall, by an order under his seal, appoint: Provided that no rent-free holding of which the annual value is less than five taka shall be liable to pay any portion of the expenses of erecting boundary-marks under this Act.