Studies on the Life-Cycle of \u3ci\u3e Ornithodiplostomum ptychocheilus\u3c/i\u3e (Faust) (Trematoda: Strigeoieda) and the Self Cure of Infected Fish*

During the summer of 1956 the following fish of Turtle River (Arvilla), North Dakota were found infected with the Neascus metacercaria of Ornithodiplostomum ptychocheilus (Faust): Northern common shiner (Notropis cornutus frontalis), bigmouth shiner (Notropis d. dorsalis), creek chub (Semotilus a. atromaculatus), fathead (Pimephales p. promelas), and johnny darter (Boleosoma n. nigrum). The cysts were usually very numerous (up to 400 per fish) in the mesenteries of the chub and common shiner; they were also very numerous in the cranial cavity and in the fat bodies behind the eyes of the common shiner and fathead, but were never seen in these locations in the chub. These unusual locations were briefly reported previously (Hoffman, 1954). Only 1 specimen of O. ptychocheilus was found in the mesenteries of the johnny darters examined