On page 351 of this magazine Professor Cockerell notes his observation of the Pogonomyrmex occidentalis at Ruleton, within twelve miles of the western limit of Kansas, and considers this as the indication of the eastern limit or beginning of the arid region. Our investigations of the range of this large ant in Kansas have shown us that its eastern limit is found far to the east of the point mentioned. The species occurs as far east in this State as the Sixth Principal Meridian, or in the counties of Republic, Ottawa, McPherson and Sedgwick, on a line about two-fifths of the length of the State from the eastern border. One would scarcely be acquainted with climatic conditions in Kansas who should consider this ant as a mark of the “arid region,” as west of the line indicated are found some of the best farming lands of the State. Especially is this true of the wheat lands, as the counties named are among those famous for the production of this cereal. Notwithstanding its occasional occurrence along the extreme eastern limit above indicated, the favoured home of the species is really within the western hundred miles of the State, and thence west to the mountains, where in specially suitable localities it sometimes occurs in astonishing abundance.