The author of American Lions and Cats and American Wolves, Coyotes and Foxes adds horses to her animal line-up. Her technique is a conversational approach to well researched facts with on the spot observation and amusing, enlightening anecdotes. It is unfortunate that this book will inevitably compete with last season's Mustang Roundup, written and illustrated by Paul Laune. In terms of mustangs, Laune's is the better book. However, Miss Beebe's book is almost evenly split between the wild horses of the Eastern United States and the mustangs of the Southwest. It also has the advantage of bringing the mustang story up-to-date and including the story of ""Wild Horse Annie,"" the housewife who stumbled on the methods of dog food suppliers and single-handedly started the move against their brutal treatment of wild horses. The Chincoteague and Assateague ponies on the islands off the Virginia coast have quite a history, which should inherit the readers of Marguerite Henry's Misty books.