In this short, very readable book a distinguished authority reviews the major characteristics of the relatively small class of mammals--only 1/2 of a percent of the total variety of animals, composed of some 4000 species. What is apparent from the start is that Van Gelder sees man as part of this group and sees the group as a whole. So when he goes on to describe, more or less from a behavioral standpoint, the birth, temperature-controlling mechanisms, territoriality, defense and offense techniques, social behavior, and reproduction, he mixes the species. He'll describe how the kangaroo can thwart a chasing predator by bounding off at right angles, or how the American pronghorns, the fastest runners in North America, may be trapped by their own curiosity--coming close to a hunter who may wave a handkerchief. The result is a fine potpourri of facts set against a background of mutual dependence and relation with nature. The importance of carnivores and herbivores, domestic and domesticated animals, and the abuses man has wrought are summed up in an eloquent last chapter, ""The Value of Mammals.