Chapter 1. Introduction.- Chapter 2. Morphology of Free-living Nematode.- Chapter 3. Materials and Methods.- Chapter 4. Systematics and taxanomy.- Chapter 5. Order Araeolaimida De Coninck & Schuurmans Stekhoven, 1933.- Chapter 6. Order Chromadorida Chitwood, 1933.- Chapter 7. Order Desmodorida De Coninck, 1965.- Chapter 8. Order Desmoscolecida Filipjev, 1929.- Chapter 9. Order Monhysterida Filipjev, 1929.- Chapter 10. Order Plectida Gadea, 1973.- Chapter 11. Order Enoplida Filipjev, 1929.- Index to families, genera and species.