Cyclostomes are the unique jawless vertebrates holding a significant position in the history of vertebrate evolution. They are the sole survivors of once flourishing group of the Paleozoic agnathans. This title provides an integrated account of lampreys and hagfishes including their palaeontology, physiology, biochemistry, endocrinology, ecology and behaviour. This comprehensive assessment will be a valuable reference for all those working on the vertebrate evolutionary and comparative studies in the related fields of biology. The text covers all aspects of the natural history of these jawless creatures.