In the course of examining rumen contents obtained from 25 domestic cattle (Bos taurus) in the vicinity of Izmir, Turkey, two somewhat similar but unusual forms of entodinia were observed. These ciliates were observed in three oi the animals and this study reports on their classification into two species, Entodinium dalli Dehority, 1974 and a new species, Entodinium williamsi n. sp. All the protozoa identified as belonging to E. dalli were distinguished as a new forma, E. dalli f. rudidorsospinatum n, f. of the basis of their caudal spines. The species Entodinium williamsi n. sp. was also divided into two formae, E, williamsi f. williamsi n. f. and E. williamsi f. turcicum n. f. The morphological characteristics of these protozoa are described and their relationships to similar entodiniid species are discussed.