The Principal Diseases of Lower Vertebrates presents the material published by Heinz H. Reichenbach-Klinke between 1957 and 1962 in three separate volumes as ""Krankheiten der Aquarienfische"" (Alfred Kernen, Stuttgart), ""Krankheiten der Amphibien,"" and ""Krankheiten der Reptilien"" (Gustav Fischer, Stuttgart). The scope of the work has been enlarged with material contributed by E. Elkan who has also done the translation. Representatives of the main groups of parasites affecting fish have been presented as far as possible. The book is organized into three parts covering the diseases of fishes, amphibians, and reptiles. Experience has shown that those who keep, or are interested in, one kind of lower vertebrate will sooner or later also take an interest in one of the other groups. It was therefore thought expedient to include what is at present known of lower vertebrate pathology in one volume, even at the risk of some repetition where fishes, amphibians, and reptiles suffer from similar diseases or are the victims of identical parasites.