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deltidium

noun
del·​tid·​i·​um
plural deltidia\-​dēə \

Definition of deltidium 

1 : a plate partly or wholly closing the delthyrium of certain brachiopods

— called also pseudodeltidium

2 : a pair of plates not homologous with the pseudodeltidium that performs the same function in other brachiopods

— called also deltidial plates

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History and Etymology for deltidium

New Latin, from Greek delta + New Latin -idium

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