Abstract
The cellular and syncytial components of the mature uterine bell of the palaeacanthocephalan, Polymorphus minutus are described, and compared with previous accounts of the histology of uterine bells. Each uterine bell always contains 17 separately distinguishable nuclei. This situation provides a good illustration of the phenomenon of organ eutely, common in Acanthocephala. The luminal spaces of the bell are described and their relevance to the translocation of eggs discussed.I should like to thank Dr D. W. T. Crompton for his help and encouragement during the course of this work and Dr P. Tate for the provision of facilities. The work was carried out during the tenure of an S.R.C. Research Studentship.