In addition to the bonds authorized under Section 65-33-7, said board shall have the authority, and it is hereby authorized, to issue and sell callable mortgage and revenue bonds in an amount not exceeding four million dollars ($4,000,000.00) to provide additional funds, if found by the board to be necessary for the purposes of Sections 65-33-1 through 65-33-15, which mortgage and revenue bonds shall be secured by a mortgage indenture on any land acquired by the board under the authority of said sections and, in the discretion of the board, by tolls to be fixed and collected by the board for the use of any such bridge or bridges, causeway or causeways, or other structure, and by any other revenue derived from any source under said sections.

Such bonds shall be in the denomination of one thousand dollars ($1,000.00) each, all shall mature within twenty-five years from the date of issuance, with such dates of maturity not to exceed twenty-five years as may be fixed in the resolution authorizing their issuance, shall bear interest not to exceed six per cent (6%) per annum to accrue and be payable semiannually, and shall be executed and sold in the manner authorized for the execution and sale of bonds, as provided in Section 65-33-7.

To secure the payment of such mortgage and revenue bonds and to fix the rights of the holders thereof, said board may execute a trust indenture constituting a mortgage lien upon any of the lands acquired under the provisions of Sections 65-33-1 through 65-33-15, and which indenture may, in the discretion of the board, pledge and assign any revenues and tolls which the board may fix and collect for the use of any bridge or bridges, causeway or causeways, or other structure financed under the provisions of said sections. Said indenture shall contain such provisions and conditions as the board may find necessary or proper, shall include provisions for insurance of such bridges or causeways against such hazards as the board may deem proper and necessary, and shall fix the terms and conditions for calling said mortgage and revenue bonds for prepayment before their maturities.