Ninety-six species of mammals are native to the Trans-Pecos region of Texas--that portion of the state which lies west of the Pecos River and contains the main representation of the Chihuahuan Desert in the United States in addition to Texas' only true mountains. The greatly varied terrain, climate, and vegetation of the Trans-Pecos make its mammal life exceptionally varied as well. In the region may be found mammals ranging from tiny shrews to great elks, from bats to aquatic beavers and muskrats, from desert-dwelling kangaroo rats to forest-loving chipmunks, and from timid mice and rats to predatory cougars and coyotes. The Mammals of Trans-Pecos Texas is intended to provide a guide to the identification of these animals and to summarize important facts about their lives. Nearly every species is illustrated with accurate, detailed pen-and-ink drawings by artist Chester O. Martin. The account of each species in the text is arranged to contain (1) a brief description of the mammal, with emphasis on its distinguishing features and size; (2) the geographic distribution of the species, with reference to an accompanying distribution map; and (3) a discussion of some of the basic life history of the mammal, including habitat preferences, reproduction, and food habits.