§ 40. Use of terms. In this chapter the Seneca Indians residing on the Allegany and Cattaraugus reservations are designated the Seneca nation, and the Seneca Indians residing on the Tonawanda reservation are designated the Tonawanda nation. For the purposes of voting and holding office, the Seneca Indians residing on the Corn-planter reservation in the New York Indian agency shall be treated as residents of the Allegany reservation. The councilors of the Seneca nation, and the chiefs of the Tonawanda nation, in council assembled, are designated, in this chapter, the council of each of such nations, respectively.