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Keywords from Image Description:
Radiolaria Challenger Plate . follows Plate Stephanida et Semantida Diam Fig Semantis sigillum sp Fig Semantis biforis sp Fig Semantrum tetrastoma sp Fig Semantrum signarium sp Fig Semantrum quadrifore sp Fig Semantidium hexastoma sp Fig Semantidium signatorium sp Fig Clathrocircus stapedius sp Fig Clathrocircus