The morphogenesis of the hypotrichous ciliate Cyrtohymena muscorum (Kahl,, 1932) Foissner, 1989 was investigated. 15 stages of the cortical and nuclear fission are described and depicted. The overall pattern of the morphogenetic events is very similar to that known from other Oxytrichidae. The morphogenesis starts with a „de novo“ - proliferation of basal bodies between the postoral ventral cirri and the left marginal row. The 6 anlagen for the frontoventral cirri of the proter and the opisthe are of different origin and evolve separately. 2 anlagen of the proter evolve from the posterior parental frontal cirri, 1 from the buccal cirrus, 1 from the paroral membrane and 2 develop „de novo“. In the opisthe 3 anlagen evolve each from the oral primordium and the postoral ventral cirri. The development of the dorsal kineties proceeds according to type 4 of Foissner & Adam , (1983 b) and shows no special features. In the middle stages of morphogenesis the paroral and endoral membrane are situated parallel. They overcross themselves in late stages and the genusspecific figure is obtained just after cell fission. The comparison with the morphogenesis of species of the genus Oxytricha shows, that morphogenetic details are not useful for separating groups at the genus level.