Said bonds shall express upon their face that they were issued by authority of this chapter, stating its title and date of approval, that the district reserves the right to pay on account of the principal thereof annual installments at a greater rate than the minimum rate stated in the bonds, that said bonds are transferable only on the registration book of the county treasurer's office at which said bonds are payable; that any attempted transfer of said bonds not recorded in said registration book shall be void so far as the rights of the district are concerned and that said bonds are of equal priority, payable with interest on a pro rata basis from revenues derived from annual assessments levied against the irrigable benefited lands within the district.