Comparative Physiology: Primitive Mammals attempts to dispel the widely held notion that ‘primitive’ animals are less advanced or less complex than the ‘non-primitive’. The term ‘primitive’, or more accurately ‘conservative’, refers to the fact that these animals have retained many of the characteristics of their evolutionary ancestors. Because they have been able to adapt to a variety of environmental conditions, these so-called primitive animals should be considered highly successful evolutionary solutions. The papers contained in this volume are the result of the Fourth International Conference on Comparative Physiology held at Crans-sur-Sierre in 1978. The conference, which was sponsored by the Interunion Commission on Comparative Physiology representing the International Unions of Biological Sciences, Physiological Sciences, and Pure and Applied Biophysics, brought together scientists from various fields to discuss the widely scattered information on primitive mammals from the perspective of comparative physiology.