§ 12. Highways on tribal lands. Commissioners of highways of towns in which an Indian reservation is wholly or partly situated shall have the same power and jurisdiction over the portion of the reservation in their respective towns, to improve highways already laid out therein, as is conferred upon such commissioners by the highway law, except that the written decision of the commissioners shall be served upon the agent, attorney or some other officer of the nation, tribe or band occupying such reservation; from which decision, such Indians may, within sixty days after the service thereof, appeal to the county judge of the county in which such lands are situated, whose decision shall be final. Such commissioners of highways may, with the consent of the tribal or national authorities of the nation, tribe or band occupying such reservation, lay out and establish as provided by law, highways on or across such reservation, and the highway commissioners of the town shall thereafter be charged with the maintenance of such road and the bridges thereon. This section shall not authorize the taxation of an Indian who is not a citizen.