Published online by Cambridge University Press: 06 April 2009
During my stay at the Zoological Station of Wimereux, Pas de Calais, France, in August 1934, I made a special study of Protozoa parasitic in marine fishes. The examination of ten specimens of young Raia batis revealed a coccidial infection in two individuals, measuring about 25 cm. in length. In one of these the mucus in the terminal portion of the intestine contained a few unsegmented spherical oocysts, with diameters from 24 to 28μ. Sections of different portions of the intestine and of the liver failed to exhibit any stages of schizogony or gametogony, evidently owing to the fact that there was a single infection at the end-phase. However, the second skate showed very numerous unsegmented oocysts in the posterior portion of the alimentary canal (Pl. I, fig. 1). This specimen provided material for the morphological study and biological observations which follow.