The opportunity to prepare a second edition of a book that was originally written 30 years ago has provided me with both a challenge and a source of pleas- over ure; the former as it needed to be spatially constrained within its original limits. Nevertheless, over 1000 references have been added. I must apologize to the many biologists whose contributions could not be included. I have attempted to keep the original format and historical perspective. The information has been princi- pally described within the context of each phyletic group of the vertebrates and their habitats. Each chapter is...