RESUMEN
The present study was performed with the help of scanning electron microscope and refers to the external morphology of the cysts of the free-living amoebae. The amoebae belonging to the genus Naegleria form cysts whose outer layer shows no wrinkles. It can be smooth (N. fowleri) or rough (N. gruberi). The average number of pores varies between 1.2 and 7.2. Their margin can be smooth (N. fowleri) or pierced (N. gruberi). The thickness of the bordering cell wall varies between 0.4 and 1.0 micrometer and that of the pore is about 0.6 micrometer. The cysts of the genera Schizopyrenus, Tetramitus and Didascalus are very small, show no wrinkles in their cell wall and contain no pores. In contrast, cysts in the general Acanthamoeba show their outer layer superficially plugged with a lesser number of wrinkles (A. rhysodes, A. culbertsoni) or with large or deep wrinkles inside their wall (. castellanii, A. polyphaga). There are no pores observed in their cysts. Thus the distinguishing morphological features of the cysts have generated important role in the taxonomy of the amoebae of the limax-group.