Beginning at the southeast corner of section sixteen, township sixty-four, range thirteen, west; thence north with the subdivisional lines to the northern boundary line of this state; thence west along the state line to the middle of the main channel of the Chariton River; thence down the said river, in the middle of the main channel thereof, to a point where it intersects the subdivisional line crossing and dividing into equal parts township sixty-four of range sixteen, west; thence east with the subdivisional lines to the place of beginning.