With the exception of the reconnaissance of 1881, I have had the assistance of Mr. Willard D. Johnson in all matters relating to topography throughout both the field and office work connected with the preparation of this volume. The energy and completeness with which he has carried for ward his special work under peculiar difficulties, not met with outside the desert regions of the Far West, deserve the highest praise The accuracy. Of the accompanying maps that Mr. Johnson has drawn from his own sur vey will make them a reliable basis for determining future changes in the lakes and rivers of the, region explored.