After publication of our "Turtles of the United States" in 1972, we discussed the possibility of preparing a companion volume on the identification and relationships of all the world's turtles. We recognized there was a definite need for such a volume, for many of the 288 species of living turtles have been poorly described and are difficult to identify.
The first serious attempt at a monograph covering the turtles, with descriptions and illustrations for identification, was by Gray (1831b) in which he summarized the then-known species. That volume spurred research on turtles which resulted in a number of new species being described. In 1835 and 1851, A. M. C. Duméril and his colleagues published lists and descriptions of the turtles in the Muséum d'Histoire Naturelle, Paris.
In 1856, Gray published a second volume based on the turtles at the British Museumof Natural History, which was the most extensive collection at that time. A supplement was published by Gray in 1870(b), and a further appendix in 1872. After Gray's death Boulenger (1889) published a new edition which included excellent identification keys and illustrations of the turtles in the British Museum. Although Siebenrock (1909) published a later list, Boulenger's (1889) catalogue is still the most scholarly identification reference for the classification and identification of turtles. Unfortunately, only about 70 percent of the now-recognized species are included in Boulenger's work, and most of the taxonomic names have changed; one must have a previous comprehensive knowledge to use it.
More recent general books on turtles by Wermuth and Mertens (1961, 1977) and Pritchard (1967, 1979) are of limited use in identifying turtles. Therefore, it is clear that there is a need for a modern volume summarizing the classification of turtles with clear descriptions and keys to their identification. After a long delay we attempted to do this in 1989 in our book "Turtles of the World", endeavoring to present the material in such a form as to be useful to both scientists and interested laypersons. We also indicated then existing problems within turtle systematics, and hoped the book would spur research to solve these questions.
In that regard "Turtles of the World" was so much a success that the taxonomy of turtles changed drastically since its publication, with the description of many new species, generic rearrangements, and the creation of a new family. To reflect these changes, the contents of this CD-ROM represents the current status of turtle taxonomy at the time of its preparation (as per early December 1997).