Philadelphia: W. B. Saunders Co., (1971). SIGNED hardcover first edition - An updated and revised third edition of a work that was considered a pioneer in its field when it was first published in 1961. Illustrated with drawings, photographs, maps and charts. An association copy INSCRIBED by Orr on the front endpaper to "my friend and associate" mammologist Jacqueline Schoneward, who provided some of the drawings in this volume and who worked with Orr at the California Academy of Science. Includes references at the end of each chapter, index. vii, 544 pp. ISBN: 0-721670172.