The expenses of the regional library system shall be apportioned among the participating political subdivisions on such basis as shall be agreed upon in the contract. The treasurer of the regional library board shall have the custody of the funds of the regional free library system; and the treasurers or other financial officers of the participating jurisdictions shall transfer quarterly to him all moneys collected or appropriated for this purpose in their respective jurisdictions. Such funds shall be expended only for the library service for which the county or city contracted and for no other purpose. The regional library board shall furnish a detailed report of receipts and disbursements of all funds at the regular meeting of the governing body of every participating jurisdiction after the close of the state’s fiscal year. It shall make a similar report to The Library of Virginia. The treasurer of the board shall be bonded for an amount to be determined by the board. The board may authorize the treasurer to pay bond premiums from state aid library funds.