Abstract
The morphology and reproduction of Trichodina branchicola n.sp. are described. Its total diameter is 30–54μ, and its height is 20–36μ,; the diameter of the striated ring is 19–33μ, and the diameter of the denticulate ring 10–20μ. There are 20–26 denticles in the ring, with 6–8 striations to each denticle. The denticles measure 1·5–2μ, in thickness, 3·5μ in length, each with a broad outer hook 2·3μ long and an inner ray 3·2μ long. The aboral cilia are fused at their base to form a complete membranelle.This organism is found on the gills of the following marine fishes at Plymouth: Ciliata mustela, Gaidopsaurus tricirratus, Cottus bubalis, Spinachia spinachia, Blennius pholis, B. guttorugine, Trigla lucerna and Pleuronectes platessa.The genus Vauchomia Mueller 1938 is regarded as a synonym of Trichodina.