Soil micro-arthropods, as such, have hitherto been little studied in North America. Investigations, particularly of woodland soils, near Ste Anne de Bellevue, Quebec, have, however, been in progress for several years. Micro-arthropods are present in very large numbers in most soils. They include mites, Collembola, Diplura, Protura, Symphyla, Pauropoda and pseudoscorpions.