The larval development of Merizocotyle sp., a monocotylid monogenean from the nasal fossae of Raia undulata

Abstract

The oncomiracidium of Merizocotyle sp., a monocotylid monogenean from the nasal fossae of Raia undulata, has 14 marginal hooklets. It seems probable that these larvae swim directly into the nasal fossae or are carried through the nostrils by the olfactory water current without first attaching themselves to the body skin. The marginal hooklets are then supplemented by a pair of hamuli and by 23 suckers, arranged in two concentric rings. The suckers arise as pockets in the ventral surface of the haptor and develop successively in a postero-anterior direction, the inner ring reaching completion before the outer ring.I would like to express my thanks to the Director, Professor R. Weill, and to the Staff of the Station Biologique at Arcachon in France. I am grateful to the Royal Society for a Pergamon Travel Award, which enabled me to visit Arcachon.I would also like to thank Mrs Mary Hutchinson for assistance with histological work.