The function of the brachial valve septa in plectambonitacean brachiopods



    1. John M. Hurst, Department of Geology and Mineralogy, Parks Road, Oxford, England, OXI 3PR.
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      Department of Geological Sciences. University of Birmingham, Birminghami, England B15 2TT.


Eoplectodonta transversalis (Wahlcnberg) and other sowcrbyellids have a complex arrangement of septa in the brachial valve. It is argued that the function of these is primarily to support the lophophore and to strengthen the shell, and that the septa mirror is almost exactly the shape of the lophophore. In Eoplectodonta transversalis the ontogenetic develop ment of the lophophore varies from a simple to a complcx ptycholophe. Other plectam-bonitaceans have trocholophous and schizolophous lophophores.