On the Innervation and Homologues of the Anterior End Appendages of the Eunicea (Polychaeta), with a Tentative Outline of the Fundamental Constitution of the Cephalic Nervous System of the Polychaetes

Abstract

Abstract Earlier papers dealing with the architecture of the cephalic nervous system of the Eunicea were studied. Thereby, a re‐investigation appeared necessary: the existing literature proved insufficient for detailed comparisons with other polychaete families and many earlier statements and conclusions turned out to be quite contradictory, especially as concerns the homologues of the anterior end appendages. In the present paper, the microanatomy of the brain and the innervation of, inter alia , the antennae, the nuchal organs and the alimentary canal of Hyalinoecia tubicola, Nothria conchylega, Eunice norvegica and E. pennata are described. The results are summarized in schematic diagrams and tables and compared with corresponding observations in other polychaete families. Thereby, some earlier opinions about the morphological value of the cephalic appendages of the Eunicea are strengthened while others are rejected. On the basis of the present observations and earlier results arrived at by the present author, and as an object for future discussion and criticism, a diagram of the fundamental constitution of the cephalic nervous system of the Polychaeta is tentatively outlined.