This is the second book of a series treating the hypotrichs, a major part of the spirotrichous ciliates. It summarises 230 years of morphological, morphogenetic, faunistic, and ecological data, heretofore scattered in some 1, 300 references around the world. The book provides taxonomists, cell biologists, and ecologists with a thorough survey supplying synonyms, nomenclature and systematics, and an extensive description of morphology and ecology, including almost all published records, for each species.