A unique treatise on the morphology and taxonomy of the order Mononchida. The mononchs represent a group of predatory nematodes that are natural enemies of other soil micro-organisms including plant-parasitic nematodes. The book includes detailed morphology of mononchs with emphasis on characters of taxonomic importance. Detailed diagnoses of the ordinal and familial groups and all the genera known to date are provided. A brief description of type species of each genus is followed by a complete list of all the valid species and their synonymies and an up-to-date key to species. The book is heavily illustrated with line drawings, microphotographs and SEM photographs of type or representative species. A complete bibliography until 2007 and an index are included.