"The Geographical Distribution of Animals" in 2 volumes is one of the best-known works by Alfred Russel Wallace. Extending the system developed by the British zoologist Philip Sclater for birds which divided the earth into six separate geographic regions for describing species distribution to cover mammals, reptiles and insects as well, Wallace created the basis for the zoogeographic regions still in use today. He discussed all of the factors then known to influence the current and past geographic distribution of animals within each geographic region, and provided maps showing factors, such as elevation of mountains, depths of oceans, and the character of regional vegetation, that affected the distribution of animals. Wallace summarized all the known families and genera of the higher animals and listed their known geographic distributions. Volume 1: The Principles and General Phenomena of Distribution: Introductory The Means of Dispersal and the Migrations of Animals On Zoological Region Classification as Affecting the Study of Geographical Distribution On the Distribution of Extinct Animals: The Extinct Mammalia of the Old World Extinct Mammalia of the New World Various Extinct Animals Zoological Geography: The Order of Succession of the Regions The Palæarctic Region The Ethiopian Region The Oriental Region The Australian Region Volume 2: The Neotropical Region The Nearctic Region Summary of the Past Changes and General Relations of the Several Regions Geographical Zoology: Introduction The Distribution of the Families and Genera of Mammalia The Distribution of the Families and Genera of Birds The Distribution of the Families and Genera of Reptiles and Amphibia The Distribution of the Families of Fishes The Distribution of Some of the More Important Families and Genera of Insects An Outline of the Geographical Distribution of Mollusca Summary of the Distribution and Lines of Migration of the Several Classes of Animals