Ammagnostidae is a family of trilobites in the suborder Agnostina, small, eyeless, isopygous trilobites with a thorax consisting of 2 segments only. Four genera have been assigned to it: Ammagnostus Öpik, 1967 * Ammagnostus psammius Öpik, 1967 (Type) * Ammagnostus bassus (Öpik, 1967) * Ammagnostus bella Guo & Luo, 1996 * Ammagnostus beltensis (Lochman, 1944) * Ammagnostus cryptus * Ammagnostus cylindratus Guo & Luo, 1996 * Ammagnostus duibianensis Lu & Lin, 1989 * Ammagnostus histus * Ammagnostus hunanensis * Ammagnostus integriceps Öpik, 1967 * Ammagnostus laiwuensis (Lorenz, 1906) * Ammagnostus mitis Öpik, 1967 * Ammagnostus sinensis Peng, 1987 * Ammagnostus wangcunensis Peng & RobisonHadragnostus Öpik, 1967 * Hadragnostus las Öpik, 1967 (Type) * Hadragnostus edax Fortey