This book, in three volumes, presents a detailed revision of the systematics and taxonomy of the platyhelminth class "Trematoda," subclasses "Aspidogastrea" and "Digenea," with keys for the identification of these parasites at the superfamily, family, subfamily and generic levels.The trematodes are parasitic worms infecting all vertebrate groups and include families of significance to human and animal health, with considerable economic impact. Volume 1 covers the subclass "Aspidogastrea" and order "Strigeida," while the second and third volumes will cover the orders "Echinostomida" and "Plagiorchiida."