Dillon Ripley, a star in the firmament of twentieth-century scholars and naturalists, was for twenty years an imaginatively effective secretary of the Smithsonian Institution. Roger Stone, one of a host of talented friends and admirers, has written the memoir that Dillon Ripley, because of illness, could not complete. . . . Stone’s admirably relentless scholarship celebrates just how much fun it could be ‘to go for a walk with Ripley,’ as observed by one of Dillon Ripley’s contemporaries.