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Ephemeroptera, Baetidae
Abstract:
The chorionic structures of the eggs of 9 European Baetis-species of the buceratus-, atrebatinus-, ,tiger-,
gracilis-, and muticus-group are examined under a scanning electron microscope. The surface features of the
chorion of the species studied in this paper are species-specific. V/ithin a single species-group there are no
greater conlormities ofthe features. Only B. calcaratus, B. gracilis, and perhaps B. buceratus show structures
apparently,useful for attachment. Micropylar openings are not found. The eggs ollinal instar nymphs and
subimagoes are covered with an adhesive layer. Finally, a detailed discussion is given of the results of
all 3 parts of the study.
