The person elected or appointed county treasurer under the provisions of this chapter, shall, within ten days after his election or appointment as such, enter into a surety bond or bonds with a surety company or surety companies, authorized to do business in Missouri, to the county in a sum not less than twenty thousand dollars nor more than the highest amount of money held by the treasurer at any one time during the year prior to his election or appointment, to be fixed and approved by the county commission, conditioned for the faithful performance of the duties of his office, and the cost of said bond shall be paid out of the general revenue fund of the county; provided, that the county treasurer in any county of the third class or fourth class may furnish either a personal bond or a surety bond and in case a surety bond is required by the county commission in said county said surety bond shall be paid for by said county.